Electro-optic system configured to reduce a perceived color change

ABSTRACT

An electro-optic system is provided that includes a front element having first and second surfaces, a rear element including third and fourth surfaces, wherein the front and rear elements are sealably bonded together in a spaced-apart relationship to define a chamber, and an electro-optic medium contained in the chamber, and the electro-optic medium is adapted to be in at least a high transmittance state and a low transmittance state. The electro-optic system further includes a display device in optical communication with the electro-optic element, the display device including at least one light source and is configured to emit at least a first primary and a second primary, the first and second primaries each having a first hue (h ab ) when viewed through the electro-optic element in approximately the high transmittance state and a second hue (h ab ′) when viewed through the electro-optic element in approximately the low transmittance state, wherein a change in the first and second hues (Δh ab ) for both first and second primaries is less than approximately 31 degrees.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/454,459 filed on Apr. 24, 2012, and now published as U.S.Patent Application Publication No. 2012/0243067, which is a continuationof U.S. patent application Ser. No. 12/852,790 filed Aug. 9, 2010, andnow U.S. Pat. No. 8,228,590. The disclosures of the above mentionedapplications are hereby incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to an electro-optic system, and moreparticularly, an electro-optic system configured to reduce a perceivedchange of color of light propagating through a variable electro-opticelement.

BACKGROUND OF THE INVENTION

Generally, various rearview mirrors for motor vehicles have beenproposed which change from the full reflectance mode (day) to thepartial reflectance mode(s) (night) for glare-protection purposes fromlight emanating from the headlights of vehicles approaching from therear. The reflectance is varied by positioning a transmittance alteringdevice between the viewer and the reflector. Among such devices arethose wherein the transmittance is varied by thermochromic,photochromic, or electro-optic means (e.g., liquid crystal, dipolarsuspension, electrophoretic, or electrochromic), and where the variabletransmittance characteristic affects electromagnetic radiation that atleast partly includes the visible spectrum. Devices of reversiblyvariable transmittance to electromagnetic radiation have been proposedas the variable transmittance element in variable transmittancelight-filters, variable reflectance mirrors, and display devices, whichemploy such light-filters or mirrors in conveying information. Thesevariable transmittance light filters have included windows.

In the past, information, images or symbols from displays, such asvacuum fluorescent displays, have been displayed in electrochromicrearview mirrors for motor vehicles with reflective layers on the thirdsurface or fourth surface of the mirror. In one such device the displayis visible to the vehicle occupant by removing all of the reflectivelayer on a portion of the selected layer and placing the display in thatarea. FIG. 1 shows a one type of electrochromic mirror device 10, havingfront and rear planar elements 12 and 16, respectively. A transparentconductive coating 14 is placed on the rear face of the front element12, and another transparent conductive coating 18 is placed on the frontface of rear element 16. A reflector (20 a, 20 b and 20 c), typicallyhaving a silver metal layer 20 a covered by a protective copper metallayer 20 b, and one or more layers of protective paint 20 c, is disposedon the rear face of the rear element 16. For clarity of description ofsuch a structure, the front surface of the front glass element issometimes referred to as the first surface, and the inside surface ofthe front glass element is sometimes referred to as the second surface.The inside surface of the rear glass element is sometimes referred to asthe third surface, and the back surface of the rear glass element issometimes referred to as the fourth surface. The front and rear elementsare held in a parallel and spaced-apart relationship by seal 22, therebycreating a chamber 26. The electrochromic medium 24 is contained inspace 26. The electrochromic medium 24 is in direct contact withtransparent electrode layers 14 and 18, through which passeselectromagnetic radiation whose intensity is reversibly modulated in thedevice by a variable voltage or potential applied to electrode layers 14and 18 through clip contacts and an electronic circuit.

The electrochromic medium 24 placed in space 26 may includesurface-confined, electrodeposition-type or solution-phase-typeelectrochromic materials. In an all solution-phase medium, theelectrochemical properties of the solvent, optional inert electrolyte,anodic materials, cathodic materials, and any other components thatmight be present in the solution can be selected, such that nosignificant electrochemical or other changes occur at a potentialdifference which oxidizes anodic material and reduces the cathodicmaterial other than the electrochemical oxidation of the anodicmaterial, electrochemical reduction of the cathodic material, and theself-erasing reaction between the oxidized form of the anodic materialand the reduced form of the cathodic material.

In most cases, when there is no electrical potential difference betweentransparent conductors 14 and 18, the electrochromic medium 24 in space26 is essentially colorless or nearly colorless, and incoming light (

_(O)) enters through front element 12, passes through transparentcoating 14, electrochromic containing chamber 26, transparent coating18, rear element 16, and reflects off layer 20 a and travels backthrough the device and out front element 12. Typically, the magnitude ofthe reflected image (

_(R)) with no electrical potential difference is about forty-fivepercent (45%) to about eighty-five percent (85%) of the incident lightintensity (

_(O)). The exact value depends on many variables outlined below, suchas, for example, the residual reflection (

_(R)) from the front face of the front element, as well as secondaryreflections from the interfaces between: the front element 12 and thefront transparent electrode 14, the front transparent electrode 14 andthe electrochromic medium 24, the electrochromic medium 24 and thesecond transparent electrode 18, and the second transparent electrode 18and the rear element 16. These reflections are well known in the art andare due to the difference in refractive indices between one material andanother as the light crosses the interface between the two. If the frontelement and the back element are not substantially parallel, then theresidual reflectance (

_(R)) or other secondary reflections will not superimpose with thereflected image (

_(R)) from mirror surface 20 a, and a double image will appear (where anobserver would see what appears to be double (or triple) the number ofobjects actually present in the reflected image).

There are minimum requirements for the magnitude of the reflected imagedepending on whether the electrochromic mirrors are placed on the insideor the outside of the vehicle. For example, according to somerequirements from most automobile manufacturers, inside mirrors have ahigh end reflectivity greater than fifty-five percent (55%) and in somecases approximately of at least seventy percent (70%), and outsidemirrors have a high end reflectivity of at least thirty-five percent(35%).

Electrode layers 14 and 18 are connected to electronic circuitry whichis effective to electrically energize the electrochromic medium, suchthat when a potential is applied across the transparent conductors 14and 18, electrochromic medium in space 26 darkens, such that incidentlight (

₃) is attenuated as the light passes toward the reflector 20 a and as itpasses back through after being reflected. By adjusting the potentialdifference between the transparent electrodes, such a device canfunction as a “gray-scale” device, with continuously variabletransmittance over a wide range. For solution-phase electrochromicsystems, when the potential between the electrodes is removed orreturned to zero, the device spontaneously returns to the same,zero-potential, equilibrium color and transmittance as the device hadbefore the potential was applied. Other electrochromic materials areavailable for making electrochromic devices. For example, theelectrochromic medium may include electrochromic materials that aresolid metal oxides, redox active polymers, and hybrid combinations ofsolution-phase and solid metal oxides or redox active polymers; however,the above-described solution-phase design is typical of most of theelectrochromic devices presently in use.

Others have the reflector on the third surface of the structure whichsimultaneously acts as an electrode for the electrochromic system. Overtime, the reflective surface has changed from being on the fourthsurface to being on the third surface. Silver or silver alloys such assilver gold are commonly used as the third surface reflector electrode.The thickness of the silver gold layer is commonly adjusted such thatthe system has a so-call transflective property, wherein the system hasboth appreciable transmittance and reflectance. Silver based materialsare particularly well suited for this application due to their lowabsorption of visible light. Displays are often placed behindtransflective systems. The transflective nature of the system shieldsthe display from the viewer providing a stealthy characteristic.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an electrochromicsystem is provided that includes an electrochromic element that has afront element having first and second surfaces, a rear element includingthird and fourth surfaces, wherein the front and rear elements aresealably bonded together in a spaced-apart relationship to define achamber, such that the second surface and the third surface face oneanother, a transparent first electrode including a layer of conductivematerial carried on the second surface, an electrochromic mediumcontained in the chamber, wherein the electrochromic medium is adaptedto be in at least a high transmittance state and a low transmittancestate, and an at least partially transmissive, partially reflectivesecond electrode. The electrochromic system further includes a displaydevice in optical communication with the electrochromic element, thedisplay device including at least one light source, and being configuredto emit at least a first primary and a second primary, and the first andsecond primaries each having a first hue (h_(ab)) when viewed throughthe electrochromic element in approximately the high transmittance stateand a second hue (h_(ab)′) when viewed through the electrochromic devicein approximately the low transmittance state, wherein a change in thefirst and second hues (Δh_(ab)) for both first and second primaries isless than approximately 31 degrees.

According to another aspect of the present invention, a rearview mirroris provided that includes an electro-optic element that has a frontelement having first and second surfaces, a rear element including thirdand fourth surfaces, at least one reflective surface, and anelectro-optic medium in optical communication between the front elementand the rear element, wherein the electro-optic medium is configured toadjust between at least a high transmittance state and a lowtransmittance state. The rearview mirror also includes a display devicein optical communication with the electro-optic element, the displaydevice including at least one light source, and being configured to emitat least a first primary and a second primary, and the first and secondprimaries each having a first hue (h_(ab)) when viewed through theelectro-optic element in approximately the high transmittance state anda second hue (h_(ab)′) when viewed through the electro-optic element inapproximately the low transmittance state, wherein a change in the firstand second hues (Δh_(ab)) for both first and second primaries is lessthan approximately 31 degrees.

According to another aspect of the present invention, an electrochromicsystem is provided that includes an electrochromic element that has afront element having first and second surfaces, a rear element includingthird and fourth surfaces, wherein the front and rear elements aresealably bonded together in a spaced-apart relationship to define achamber, such that the second surface and the third surface face oneanother, a transparent first electrode including a layer of conductivematerial carried on the second surface, an electrochromic mediumcontained in the chamber, wherein the electrochromic medium is adaptedto be in at least a high transmittance state and a low transmittancestate, and a partially transmissive, partially reflective layer. Theelectrochromic system further includes a display device in opticalcommunication with the electrochromic element, the display deviceincluding at least one light source, and being configured to emit atleast one primary that is light having at least one of a yellow hue andan amber hue, and the at least one primary having a first hue (h_(ab))when viewed through the electrochromic element in approximately the hightransmittance state and a second hue (h_(ab)′) when viewed through theelectrochromic device in approximately the low transmittance state,wherein a change in the first and second hues (Δh_(ab)) is less thanapproximately 55 degrees.

According to yet another aspect of the present invention, anelectrochromic system is provided that includes an electrochromicelement that has a front element having first and second surfaces, arear element including third and fourth surfaces, wherein the front andrear elements are sealably bonded together in a spaced-apartrelationship to define a chamber, such that the second surface and thethird surface face one another, a transparent first electrode includinga layer of conductive material carried on the second surface, anelectrochromic medium contained in the chamber, wherein theelectrochromic medium is adapted to be in at least a high transmittancestate and a low transmittance state, and a partially transmissive,partially reflective layer. The electrochromic system further includes adisplay device in optical communication with the electrochromic element,the display device including at least one light source, and beingconfigured to emit a primary that is light having a blue hue, and theprimary having a first hue (h_(ab)) when viewed through theelectrochromic element in approximately the high transmittance state anda second hue (h_(ab)′) when viewed through the electrochromic device inapproximately the low transmittance state, wherein a change in the firstand second hues (Δh_(ab)) is less than approximately 49 degrees.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a cross-sectional view of a prior art electrochromic mirrorassembly;

FIG. 2 is a front elevational view schematically illustrating aninside/outside electrochromic rearview mirror system for motor vehicles,wherein the inside and outside mirrors incorporate an electro-opticsystem, in accordance with one embodiment of the present invention;

FIG. 3 is a cross-sectional view of the inside electrochromic rearviewmirror incorporating a third surface reflector/electrode illustrated inFIG. 2, taken on the line III-III thereof, in accordance with oneembodiment of the present invention;

FIG. 4 is a cross-sectional view of an electrochromic mirrorincorporating an alternate embodiment of a third surfacereflector/electrode, taken on the line IV-IV of FIG. 2, in accordancewith one embodiment of the present invention;

FIG. 5A is a cross-sectional view of an electrochromic system having animproved arrangement for applying a drive potential to the transparentconductor on the second surface of the mirror, in accordance with oneembodiment of the present invention;

FIG. 5B is a top view of the third surface reflector of FIG. 5A, inaccordance with one embodiment of the present invention;

FIG. 6 is a cross-sectional view of an electrochromic system using acured and machine-milled epoxy seal to hold the transparent elements ina spaced-apart relationship, in accordance with one embodiment of thepresent invention;

FIGS. 7A-7H are partial cross-sectional views of alternativeconstructions of an electrochromic system, in accordance with variousembodiments of the present invention;

FIG. 8 is a partial cross-sectional view of an electrochromic system, inaccordance with one embodiment of the present invention;

FIGS. 9A-9G are partial cross-sectional views of additionalconstructions of an electrochromic system, in accordance with variousembodiments of the present invention;

FIG. 10 is a diagram illustrating characteristics of an emitted lightwith respect to a*, b*, C*, and hue values;

FIG. 11 is a chart illustrating changes in h_(ab) for various primariesemitted from a display device that are viewed through an electrochromicmedium that is altered between approximately a high transmittance stateand approximately a low transmittance state, in accordance with oneembodiment of the present invention;

FIG. 12 is a chart illustrating a comparison of light absorption by anelectrochromic medium with respect to wavelength for a prior artelectrochromic element and an electrochromic medium in accordance withone embodiment of the present invention;

FIG. 13 is a chart illustrating a spectrum of visible light;

FIG. 14 is a chart illustrating in the L*a*b* color space, a* and b*being converted into C* and a hue;

FIG. 15A is a chart illustrating a comparison of a perceived change incolor in the u′,v′ color space as a transmittance state varies for aprior art electrochromic element and an electrochromic system inaccordance with one embodiment of the present invention;

FIG. 15B is a table illustrating a comparison of a perceived colorchange in the u′,v′ color space illustrated in FIG. 15A;

FIG. 16A is a chart illustrating a reflected color of an electrochromicsystem as an electrochromic medium alters transmittance states, inaccordance with one embodiment of the present invention;

FIG. 16B is a chart illustrating a reflected color of a prior artelectrochromic element as an electrochromic medium alters transmittancestates;

FIGS. 17A-17B are tables illustrating various examples of perceivedcolor change, in accordance with various embodiments of the presentinvention and the prior art;

FIG. 18 is an electrical circuit diagram in block and schematic form forcontrolling a contrast ratio of a display associated with anelectrochromic mirror, in accordance with one embodiment of the presentinvention;

FIG. 19 is a block diagram of a display device, in accordance with oneembodiment of the present invention;

FIG. 20 is a schematic diagram of an electrochromic system, inaccordance with one embodiment of the present invention;

FIG. 21 is a perspective view of a rearview mirror assembly having adisplay device that includes a sensor, in accordance with one embodimentof the present invention;

FIG. 22 is a perspective view of the display device of FIG. 21;

FIG. 23 is a chart illustrating examples of transmittance at variouswavelengths in an electrochromic system at various applied potentials,in accordance with one embodiment of the present invention;

FIG. 24 is a table illustrating ΔE_(u′,v′) for exemplary primaries, inaccordance with one embodiment of the present invention;

FIG. 25 is a chart illustrating examples of u′,v′ values at variouswavelength combinations, in accordance with one embodiment of thepresent invention;

FIG. 26 is a chart illustrating exemplary intensity ratio differences atvarious wavelengths, in accordance with one embodiment of the presentinvention;

FIG. 27 is a chart illustrating exemplary intensity ratio differences atvarious wavelengths, in accordance with one embodiment of the presentinvention;

FIG. 28 is a chart illustrating examples of u′,v′ values at variouswavelength combinations, in accordance with one embodiment of thepresent invention;

FIG. 29 is a table illustrating ΔE_(u′,v′) for exemplary primaries, inaccordance with one embodiment of the present invention;

FIG. 30 is a chart illustrating examples of u′,v′ values at variouswavelengths, in accordance with one embodiment of the present invention;

FIG. 31 is a table illustrating ΔE_(u′,v′) values for exemplaryprimaries, in accordance with one embodiment of the present invention;

FIG. 32 is a table illustrating ITO thickness with respect to lowreflectance state percentage, in accordance with one or more embodimentsof the present invention;

FIG. 33 is a table illustrating a reflectance in low reflectance statewith respect to exemplary stacks, in accordance with one or moreembodiments of the present invention;

FIG. 34A is a table illustrating calculated reflective color for variousidealized thin film stacks in the low reflectance state, in accordancewith one or more embodiments of the present invention;

FIG. 34B is a table illustrating three examples of coating stacks thatcan provide neutral reflected color, in accordance with one or moreembodiments of the present invention;

FIG. 35 is a cross-sectional view of an electrochromic system thatincludes a graded transition between an opaque area and a display area,in accordance with one embodiment of the present invention;

FIG. 36 is a table illustrating various characteristics of a stack in anelectrochromic system, in accordance with one or more embodiments of thepresent invention;

FIG. 37 is a table illustrating various characteristics of a stack in anelectrochromic system, in accordance with one or more embodiments of thepresent invention;

FIG. 38 is a cross-sectional view of an electrochromic system, inaccordance with one embodiment of the present invention;

FIG. 39 is a table of characteristics of a stack in an electrochromicsystem, in accordance with one embodiment of the present invention;

FIG. 40 is a chart illustrating an output from a display device, inaccordance with one embodiment of the present invention;

FIG. 41A is a chart illustrating an output of light viewed through anelectrochromic medium in approximately its high transmittance state, inaccordance with one embodiment of the present invention;

FIG. 41B is a chart illustrating an output of light viewed through anelectrochromic medium in approximately its low transmittance state, inaccordance with one embodiment of the present invention;

FIG. 42 is a diagram illustrating light passing through an electro-opticdevice, in accordance with one embodiment of the present invention;

FIG. 43A is a diagram illustrating rings or gradient of potential, inaccordance with one embodiment of the present invention; and

FIG. 43B is a diagram illustrating non-uniform cell spacing, inaccordance with one embodiment of the present invention.

DETAILED DESCRIPTION

With respect to FIG. 2, an inside mirror assembly 110 and two outsiderearview mirror assemblies 111 a and 111 b are schematically illustratedfor the driver-side and passenger-side, respectively, all of which canbe adapted to be installed on a motor vehicle in a conventional mannerand where the mirrors face the rear of the vehicle and can be viewed bythe driver of the vehicle to provide a rearward view, according to oneembodiment. The inside mirror assembly 110 and the outside rearviewmirror assemblies 111 a and 111 b may incorporate light-sensingelectronic circuitry of the type illustrated and described in CanadianPatent No. 1,300,945, entitled “AUTOMATIC REARVIEW MIRROR SYSTEM FORAUTOMOTIVE VEHICLES,” U.S. Pat. No. 5,204,778, entitled “CONTROL SYSTEMFOR AUTOMATIC REARVIEW MIRRORS,” U.S. Pat. No. 5,451,822, entitled“ELECTRONIC CONTROL SYSTEM,” U.S. Pat. No. 6,359,274, entitled“PHIOTODIODE LIGHT SENSOR,” U.S. Pat. No. 6,402,328, entitled “AUTOMATICDIMMING MIRROR USING SEMICONDUCTOR LIGHT SENSOR WITH INTEGRAL CHARGECOLLECTION,” U.S. Pat. No. 6,379,013, entitled “VEHICLE EQUIPMENTCONTROL WITH SEMICONDUCTOR LIGHT SENSORS,” or U.S. Pat. No. 7,543,946,entitled “DIMMABLE REARVIEW ASSEMBLY HAVING A GLARE SENSOR,” the entirereferences hereby being incorporated herein by reference, and othercircuits capable of sensing glare and ambient light and applying a drivepotential to the electrochromic element. The mirror elements containedin the mirror assemblies 110, 111 a, and 111 b are essentially identicalin that like numbers identify like components of the inside and outsidemirrors 110, 111 a, 111 b. These components may be slightly different inconfiguration, but function in substantially the same manner and obtainsubstantially the same results as similarly numbered components. Forexample, the shape of the front glass element of the inside mirror 110is generally longer and narrower than the outside mirrors 111 a and 111b. There are also some different performance standards placed on theinside mirror 110 as compared to the outside mirrors 111 a and 111 b.For example, the inside mirror 110 generally, when fully cleared, shouldhave a reflectance value of greater than fifty percent (50%), and insome cases of about fifty-five percent (55%) to about eighty-fivepercent (85%) or higher, whereas the outside mirrors often have areflectance of about forty percent (40%) to about sixty-five percent(65%). Also, in the United States (as supplied by the automobilemanufacturers), the passenger-side mirror 111 b typically has a convexshape, whereas the driver-side mirror 111 a and inside mirror 110presently must be flat. In Europe, the driver-side mirror 111 a iscommonly flat or aspheric, whereas the passenger-side mirror 111 b has aconvex or aspheric shape. In Japan, both outside mirrors have a convexshape. The following description is generally applicable to all mirrorassemblies of the present invention.

Regarding to FIG. 3, an exemplary cross-sectional view of mirrorassembly 110 is illustrated having a front transparent element 112having a front or first surface 112 a and a rear or second surface 112b, and a rear element 114 having a front or third surface 114 a and arear or fourth surface 114 b. For clarity of description of such astructure, the following designations will be used hereinafter. Thefront surface 112 a of the front transparent element 112 will bereferred to as the first surface, and the back surface 112 b of thefront transparent element 112 will be referred to as the second surface.The front surface 114 a of the rear transparent element 114 will bereferred to as the third surface, and the back surface 114 b of the reartransparent element 114 will be referred to as the fourth surface. Achamber 125 can be defined by one or more layers that make up an atleast partially transparent conductor 128 (carried on second surface 112b), a reflector/electrode 120 (disposed on third surface 114 a), and aninner circumferential wall 132 of sealing member 116. An electrochromicmedium 126 can be contained within a chamber 125. According to oneembodiment, the reference to an electrode or layer as being “carried” onat least a portion of the surface of an element, refers to bothelectrodes or layers that are disposed directly on at least a portion ofthe surface of an element or disposed at least partially on anothercoating, layer, or layers that are disposed directly on at least aportion of the surface of the element.

The front element 112, the rear element 114, and the electrochromicmedium 126 contained in the chamber 125 can be included in anelectrochromic element, generally indicated at reference identifier 134(FIGS. 3-9G, 35, and 38), according to one embodiment. A display deviceor light engine 136 (FIGS. 7A-9E, 19, 20, 35, and 38) can be in opticalcommunication with the electrochromic element 134, such that the displaydevice 136 is configured to emit light that is viewed through theelectrochromic element 134. Typically, the display device 136 can beconfigured to emit light in a plurality of colors. Alternatively, theelectrochromic medium 126 contained in the chamber 125 can be anysuitable electro-optic medium, such that an electro-optic element caninclude a front element 112, the rear element 114, and an electro-opticmedium, and the display device 136 is in optical communication with theelectro-optic element. According to one embodiment, an electrochromicsystem, generally indicated at reference identifier 138 (FIGS. 7A-9G,20-22, 35, and 38), includes the electrochromic element 134 and thedisplay device 136. The electrochromic system 138 and the electro-opticelement are described herein with respect to a rearview mirror forpurposes of explanation and not limitation, and can be other types ofsystems or devices, such as, but not limited to, an electrochromic orelectro-optic window.

The electrochromic system 138 can include an electrochromic element 134having the front element 112 including the first surface 112 a and thesecond surface 112 b, and the rear element 114 including the thirdsurface 114 a and the fourth surface 114 b, wherein the front and rearelements 112, 114 are sealably bonded together in a spaced-apartrelationship to define the chamber 125, according to one embodiment. Theelectrochromic element 134 can also include the transparent firstelectrode 128 having one or more layers with at least one of which is aconductive material carried on the second surface 112 b, theelectrochromic medium 126 contained in the chamber 125, wherein theelectrochromic medium 126 is adapted to be in at least a hightransmittance state and a low transmittance state, and a partiallytransmissive, partially reflective second electrode 120. The partiallytransmissive partially reflective second electrode 120 can be disposedover at least a portion of the third surface 114 a and/or the fourthsurface 114 b. The electrochromic system 138 can further include thedisplay device 136 in optical communication with the electrochromicelement 134, wherein the display device 136 includes at least one lightsource 140.

Generally, the electrochromic element 134 and display device 136 canhave a plurality of elements that affect the light (e.g., intensityversus wavelength and/or h_(ab)) emitted by a light source 140 of thedisplay device 136. Thus, light passing through all of the opticalelements after the light has been emitted by the light source 140, andviewed through one or more elements of the display device 136 and theelectrochromic element 134, typically has different intensity levelsacross the visible spectrum than the original light that could be vieweddirectly from the light source 140. In some embodiments, it may beimportant for the light passing through all of the components to havecertain characteristics such as meeting a certain color gamut. Inembodiments where there is not a perfect match of the color before andafter a given component, the components may be designed or selected tocompensate for weaknesses or characteristics in the other components ofthe electrochromic system 138. The electrochromic element 134, thedisplay device 136, or a combination thereof, can have one or morecomponents configured to enhance the actual perceived light due to anyadverse affects one or more components of the electrochromic element 134and the display device 136 may have on the emitted light, as describedin greater detail herein.

As illustrated in FIG. 20, by way of example, the electrochromic system138 can include the electrochromic element 134 and the display device136, wherein the display device 136 can include the light source 140 andthe display element 202. In such an embodiment, the display device 136can be an LCD. Typically, the light emitted by the light source 140includes light at various wavelengths (I_(O)). The light when viewedthrough the display element 202, which is exemplary illustrated ashaving a red filter 208, a green filter 210, and a blue filter 212.Generally, the light emitted from the light source 140 when viewedthrough the red filter 208 appears as red I_(r), the light emitted fromthe light source 140 when viewed through the green filter 210 appears asgreen I_(g), and the light emitted from the light source 140 when viewedthrough the blue filter 212 appears as blue I_(b) to generate the red,green, and blue primaries; although other primaries may be used. Thered, green, and blue primaries, I_(r), I_(g), I_(b) can blend togetherI_(w) to have a hue that can be based upon the intensity of the red,green, and blue primaries I_(r), I_(g), I_(b). The light output of thedisplay device is illustrated in the chart of FIG. 40.

These the red, green, and blue primaries I_(r), I_(g), I_(b) andcombinations thereof can be viewed through the display device 136 by theuser. The red, green, and blue primaries I_(r), I_(g), I_(b) may bealtered by the electrochromic element 134 in the high transmittancestate, wherein the altered primaries are represented in FIG. 20 byI_(r)′, I_(g)′, and I_(b)′, respectively. The output of light viewedthrough the electrochromic medium 126 in approximately the hightransmittance state is illustrated in the chart of FIG. 41A.Furthermore, the red, green, and blue primaries I_(r), I_(g), I_(b) maybe altered by the electrochromic element 134 in a reduced transmittancestate, and such altered primaries can also be represented in FIG. 20 byI_(r)′, I_(g)′, and I_(b)′, respectively. The output of light viewedthrough the electrochromic medium 126 in approximately the lowtransmittance state is illustrated in the chart of FIG. 41B. Typically,the electrochromic system 138 is configured such that the final colorshave the proper characteristics. This is, by way of example, illustratedin the charts of FIGS. 41A and 41B, which show a ratio of the red,green, and blue light that will appear approximately color neutral to aviewer when the electrochromic medium 126 is in approximately its highand low transmittance state, respectively.

As described in greater detail herein, the electrochromic element 134,the display device 136, or a combination thereof can be configured toreduce the perceived hue difference between I_(r)′, I_(g)′, and I_(b)′and when the electrochromic element 134 is in approximately the hightransmittance state and in a reduced transmittance state. This isexemplary illustrated in the chart of FIG. 40, which shows the red,green, and blue primaries projected to a level that will appearapproximately color neutral to a viewer. As described in greater detailherein, the electrochromic element 134, the display device 136, or acombination thereof can be configured to eliminate or reduce theperceived color difference between I_(r)′, I_(g)′, and I_(b)′ when theelectrochromic element 134 is driven from a high transmittance state toa reduced transmittance state. Various embodiments are proposed toachieve adequate color preservation for different applications. Oneembodiment of the present invention is illustrated in FIGS. 41A and 41B,which show the same primaries when modulated by the electrochromicelement 134 in approximately the high transmittance state andapproximately the low transmittance state.

The display device 136 can be an emissive display that uses theprinciples of additive color mixing to achieve a range of colors used inthe display device 136, according to one embodiment. Typically, inadditive color mixing three “primaries” (e.g., red, green, and blue) canbe mixed with various intensities to produce a desired color, althoughother primaries may be used.

The display device 136 can include the light source 140, and the lightsource 140 can include one or more lighting elements (e.g., lightemitting diodes (LEDs)). According to one embodiment, the light source140 can be a white lighting element. Alternatively, the light source 140can include a plurality of red, green, and blue (RGB) lighting elements.Exemplary devices are described in U.S. Patent Application Publication2008/0068520, entitled “VEHICLE REARVIEW MIRROR ASSEMBLY INCLUDING AHIGH INTENSITY DISPLAY,” and U.S. Pat. No. 6,521,916, entitled“RADIATION EMITTER DEVICE HAVING AN ENCAPSULANT WITH DIFFERENT ZONES OFTHERMAL CONDUCTIVITY,” the entire references hereby being incorporatedherein by reference.

FIG. 19 exemplary illustrates an embodiment, wherein an illuminationdevice generally indicated at reference identifier 200 is positionedbehind a display element 202 for projecting light through the displayelement 202. The display element 202 may be a dynamically variable lightshutter, such as an LCD or an electrochromic display provided on or nearthe rear element 114. Examples of display elements in the form of anappliqué positioned behind an electrochromic mirror are disclosed inU.S. Pat. No. 6,870,655, entitled “REARVIEW MIRROR DISPLAY,” the entirereference hereby being incorporated herein by reference.

The illumination device 200 may include one or more light emittingpackages, such as, but not limited to, NICHIA™ Corp. part numberNSSW064A, or packages disclosed in commonly assigned U.S. Pat. No.6,335,548, entitled “SEMICONDUCTOR RADIATION EMITTER PACKAGE,” theentire reference hereby being incorporated herein by reference. Thelight source 140 can include a plurality of lighting elements 204 and206, such as, but not limited to, LED chips or other semiconductorradiation emitters that can be provided in a single package and may beindividually activated by selective application of power to differentleads that are attached to the LED chips. At least two LED chips can beincluded in the package, with one LED 204 emitting red light and anotherLED 206 emitting green light so as to mix and form amber light that isemitted from the display device 136. It should be appreciated by thoseskilled in the art that illumination device 200 may be positionedbehind, about the edges, or slightly in front of display element 202.The illumination device 200 can be used to provide backlighting for thedisplay element 202, which can be an LCD element or the like. The LCDelement used can be a twisted nematic, super twist, active matrix,dichroic, dichroic phase change, cholesteric, smectic, ferroelectric,IPS, or MVA type.

The display device 136 may be any type of photo-emissive source havingmore than one color, for example, include a vacuum fluorescent displaythat utilizes a combination of red and green phosphors (or anothercombination thereof). An example of the display device can be asubassembly, such as, but not limited to, TOSHIBA™ display part numberLTA035B3J1F with fifty percent (50%) color gamut compared to NTSC.Similarly, an LED display may be constructed utilizing two or morecolors, such as, red, green, and blue, or different colored LEDs. Thus,as broadly defined herein, the display device 136 may include one ormore “lighting elements” for emitting light of first and second colors,according to one embodiment. Such light sources may includephotoluminescent light sources such as phosphorescent or fluorescentmaterials, and/or may include electroluminescent light sources,including, but not limited to, semiconductor radiation emitters such asLEDs, OLEDs, LEPs, etc.

LEDs of the display device 136 may be of the type trade named “Pixar” byHEWLETT PACKARD. Due to the loss of light in the transflective coating,bright LEDs are needed. AlInGaP based LEDs are suitable for thisapplication and are available in green, red, amber, and various similarcolors. Blue and green colors can be achieved by using InGaN LEDs. Whenusing InGaN LEDs, there are many fewer LEDs needed than would be used ina segmented display. As an alternative to using packaged LEDs such asthe “Pixar” LED, they can be bonded to the circuit board directly usinga technique commonly known in the industry as Chip-On-Board.

Exemplary light engines or display devices are described in U.S. Pat.No. 6,639,360, entitled “HIGH POWER RADIATION EMITTER DEVICE AND HEATDISSIPATING PACKAGE FOR ELECTRONIC COMPONENTS,” U.S. Pat. No. 7,075,112,entitled “HIGH POWER RADIATION EMITTER DEVICE AND HEAT DISSIPATINGPACKAGE FOR ELECTRONIC COMPONENTS,” U.S. Pat. No. 7,489,031, entitled“HIGH POWER RADIATION EMITTER DEVICE AND HEAT DISSIPATING PACKAGE FORELECTRONIC COMPONENTS,” U.S. Pat. No. 5,803,579, entitled “ILLUMINATORASSEMBLY INCORPORATING LIGHT EMITTING DIODES,” U.S. Pat. No. 6,132,072,entitled “LED ASSEMBLY,” U.S. Pat. No. 6,523,976, entitled “WHITELIGHT-EMITTING DISCRETE LED COMPONENT, LED ASSEMBLY, AND LICENSE PLATEILLUMINATOR,” U.S. Pat. No. 7,524,097, entitled “LIGHT EMITTINGASSEMBLY,” U.S. Pat. No. 6,828,170, entitled “METHOD OF MAKING ASEMICONDUCTOR RADIATION EMITTER,” U.S. Pat. No. 7,253,448, entitled“SEMICONDUCTOR RADIATION EMITTER PACKAGE,” U.S. Pat. No. 7,342,707,entitled “INDICATORS AND ILLUMINATORS USING A SEMICONDUCTOR,” and U.S.Patent Application Publication No. 2009/0096937, entitled “VEHICLEREARVIEW ASSEMBLY INCLUDING A DISPLAY FOR DISPLAYING VIDEO CAPTURED BY ACAMERA AND USER INSTRUCTIONS,” the entire references hereby beingincorporated herein by reference.

With respect to the electrochromic element 134, the various layers orcomponents typically affect the light that is viewed through theelectrochromic element 134. The rear element 114 can have atransflective coating, such that the rear element 114 can have anoptical configuration that reflects at least a portion of light incidentfrom at least one side, and transmits at least a portion of lightincident from at least one side. Typically, the light viewed through therear element 114 can be attenuated, but can compensate for adverseattenuation effects of other components of the electrochromic element134. The transflective elements can be substantially color neutral toreduce adverse color rendering effects of the emitted light. Exemplarytransflective elements are disclosed in U.S. Provisional PatentApplication No. 60/587,113, entitled “HIGH BRIGHTNESS DISPLAY INMIRROR,” U.S. Pat. No. 7,502,156, entitled “VARIABLE REFLECTANCE MIRRORSAND WINDOWS,” U.S. Pat. No. 7,679,809, entitled “VARIABLE REFLECTANCEMIRRORS AND WINDOWS,” U.S. Patent Application Publication No.2009/0296190, entitled “REARVIEW MIRROR ASSEMBLIES WITH ANISOTROPICPOLYMER LAMINATES,” and U.S. Patent Application Publication No.2010/0165437, entitled “VARIABLE REFLECTANCE MIRRORS AND WINDOWS,” theentire references hereby being incorporated herein by reference.

Generally, the electrochromic medium 126 can be adapted to be in thehigh transmittance state, the low transmittance state, and transmittancestates intermediate thereto. When the electrochromic medium 126 is inthe high transmittance state and the display device 136 is OFF, the usercan view a reflection from the reflector. If the display device 136 isON and the electrochromic medium 126 is in the high transmittance state,the electrochromic medium 126 may slightly attenuate the emitted light.There is, however, greater attenuation of the emitted light when theelectrochromic medium is in the low transmittance state. In embodimentswhere the electrochromic system 138 is configured for a given color, thehigh transmittance state may define the reference color condition thatthe low transmittance states are compared against. The electrochromicmedium 126 can include one or more components to reduce adverse affectsof color rendering on light viewed through the electrochromic medium126.

The front element 112 may also have one or more coating layers, whichmay include a transparent electrode, which typically has a lowerreflectivity than the coating on the rear element 114. The light viewedthrough the front element 112 may be attenuated by the coating layers onthe front element 112, however, the transmittance properties of thesecoating layers may be controlled to compensate for adverse attenuationeffects of other components of the electrochromic element 134. Thetransparent electrode on the front element 112 generally has asubstantially neutral color to reduce adverse color rendering effects ofthe emitted light.

Thus, there typically is a change in intensity and/or hue (e.g., h_(ab))of light viewed directly from the display device 136 as compared tolight viewed through the electrochromic element 134, either due to theelectrochromic medium 126, substrates, coatings, or a combinationthereof. Such a change in intensity and/or hue is generally greater whenthe electrochromic medium 126 is in the low transmittance state (orintermediate states) as compared to when the electrochromic medium 126is in the high transmittance state.

In various examples described herein, references are made to thespectral properties of models of electrochromic systems constructed ormodeled in accordance with the parameters specified in each example. Indiscussing colors, it is useful to refer to the CommissionInternationale de I′Eclairage's (CIE) 1976 CIELAB Chromaticity Diagram(commonly referred to as the L*a*b* chart). The technology of color isrelatively complex, but a fairly comprehensive discussion is given by F.W. Billmeyer and M. Saltzman in Principles of Color Technology, 2ndEdition, J. Wiley and Sons Inc. (1981), and the present disclosure, asit relates to color technology and terminology, generally follows thatdiscussion, the entire reference hereby incorporated herein byreference. In describing the invention we will use three different colorspaces, which includes the CIELAB color space, Y_(x,y) color space, andthe Y_(u′,v′) color space. On the L*a*b* chart, L* defines lightness, a*denotes the red/green value, and b* denotes the yellow/blue value.Typically the electrochromic medium 126 has a transmission spectra ateach particular voltage that may be converted to a three numberdesignation, their L*a*b* values. To calculate a set of colorcoordinates, such as L*a*b* values, from the spectral transmission orreflectance, two additional items are generally needed. One is thespectral power distribution of the light source or illuminant. Thepresent disclosure uses CIE Standard Illuminant A to simulate light fromautomobile headlamps and uses CIE Standard Illuminant D₆₅ to simulatedaylight. The second item is the spectral response of the observer. Thepresent disclosure can use the 2 degree CIE standard observer. Theilluminant/observer combination generally used for mirrors is thenrepresented as A/2 degree and the combination generally used for windowsis represented as D₆₅/2 degree. The value C*, which is also describedbelow, is equal to the square root of (a*)²+(b*)², and hence, provides ameasure for quantifying color neutrality. To further describe theinvention, the CIELAB color space, in particular, the values of L*,C*_(ab) (chroma), and h_(ab) (hue) can be referenced (FIG. 10).According to one embodiment, a hue or h_(ab) can be a range or variationof colors within a particular color region (FIG. 13). In the u′,v′ colorspace we introduce the value (ΔE_(u′,v′)), defined as the square root of(Δu′)²+(Δv′)², wherein Δu′ and Δv′ are the differences in the u′ and v′for a display element (e.g., one or more primaries) viewed through theelectrochromic element 134 in approximately the high and lowtransmission (or intermediate) states, respectively.

The display device 136 can be configured to project a display element ina plurality of colors. Thus, the primaries can project the displayelement. When the display element is viewed through the electrochromicdevice 134 when in the high transmittance state, the user perceives thedisplay element in one or more colors (e.g., the first hue) h_(ab). Whenthe electrochromic device 134 is driven to a lower transmittance state,the attenuation characteristics of the electrochromic medium 126 change,which may alter the perceived color of the display element when viewedthrough the electrochromic device 134 (e.g., a second hue) h_(ab)′, ascompared to when the electrochromic element 134 is in the hightransmittance state. As described in greater detail herein, theelectrochromic element 134, the display device 136, or a combinationthereof, can be configured to reduce the change in color (Δh_(ab))(e.g., a change in the first and second hues) of the emitted lightperceived by the user when the electrochromic device 134 alters betweenthe high transmittance state and a lower transmittance state.

This hue change of the display element is quantified as Δh_(ab). TheΔh_(ab) of the display element (or the primaries) from the displaydevice 136 when viewed through the electrochromic device 134 iscontrolled by the components in the electrochromic medium 126, thecomponents of the front and rear elements 112, 114, the light emitted bythe display device 136, or a combination thereof, as described ingreater detail herein. Such control can reduce the perceived colorchange or reduce the change in h_(ab) (or the change in hue (Δh_(ab)))of the display element when the electrochromic device is driven from thehigh transmittance state to a state of lower transmittance.

FIG. 11 exemplary illustrates various h_(ab) for a display element inExample 14 having a green hue, a display element having a yellow hue,and a display element having a red hue. The h_(ab) of the displayelement can be controlled to reduce a change in h_(ab) betweentransmittance states by active control of the display device 136 (e.g.,altering light emitted by a light source 140 therein), the components ofthe electrochromic element 134, or a combination thereof. Typically, thedifference between the h_(ab) values of the display element 136 whenviewed through the electrochromic medium 126 when in approximately thehigh transmittance state and in approximately the low transmittancestate are reduced. As described herein, reducing the change in h_(ab) ofa display element from the display device 136 when viewed through theelectrochromic element 134 from its high transmittance state to its lowtransmittance state can be achieved by selecting one or more componentsin the electrochromic element 134 and/or by altering the light by thedisplay device 136 emitted to compensate for the influence of theelectrochromic medium 126 on the emitted light.

With respect to both FIGS. 11 and 14, line 200 (FIG. 11) can represent aprimary that is light having a yellow hue, which is emitted by thedisplay device 136 and viewed by a user through the electrochromicelement 134 when the electrochromic medium 126 is in approximately thehigh transmittance state. Line 202 (FIG. 11) can represent the primarythat is light having the yellow hue, which is emitted by the displaydevice 136 and viewed by a user through the electrochromic element 134when the electrochromic medium 126 is in an intermediate transmittancestate, and line 204 (FIG. 11) can represent the primary that is lighthaving the yellow hue, which is emitted by the display device 136 andviewed through the electrochromic element 134 when the electrochromicmedium 126 is in approximately the low transmittance state. Whenconsidering lines 200, 202, and 204 with respect to FIG. 11, the colorperceived by the user maintains the yellow hue even as the transmittancestate of the electrochromic medium 126 is altered between the high andlow transmittance states. Thus, a change in h_(ab) between lines 200 and204 is a value (approximately forty-five degrees (45°)) that remainsapproximately representative of light having the yellow hue, rather thanhaving a larger change in h_(ab), such that the perceived light nolonger has a yellow hue (e.g., has a green hue).

Similarly, in regards to both FIGS. 11 and 14, line 206 (FIG. 11) canrepresent a primary that is light having a red hue, which is emitted bythe display device 136 and viewed through the electrochromic element 134when the electrochromic medium 126 is in approximately the hightransmittance state. Line 208 (FIG. 11) can represent the primary thatis light having the red hue, which is emitted by the display device 136and viewed through the electrochromic element 134 when theelectrochromic medium 126 is in the intermediate transmittance state,and line 210 (FIG. 11) can represent the primary that is light havingthe red hue, which is emitted by the display device 136 and viewedthrough the electrochromic element 134 when the electrochromic medium126 is in approximately the low transmittance state. When consideringlines 206, 208, and 210 with respect to FIG. 11, the color perceived bythe user maintains the red hue even as the transmittance state of theelectrochromic medium 126 is altered between the high and lowtransmittance states. Thus, a change in h_(ab) between lines 206 and 210is a value (approximately fifteen degrees (15°)) that remainsapproximately representative of light having the red hue, rather thanhaving a larger change in h_(ab), such that the perceived light nolonger has a red hue.

Another example with respect to both FIGS. 11 and 14, is line 212 (FIG.11) representing a primary that is light having a green hue, which isemitted by the display device 136 and viewed through the electrochromicelement 134 when the electrochromic medium 126 is in approximately thehigh transmittance state. Line 214 (FIG. 11) can represent the primarythat is light having the green hue, which is emitted by the displaydevice 136 and viewed through the electrochromic element 134 when theelectrochromic medium 126 is in an intermediate transmittance state, andline 216 (FIG. 11) can represent the primary that is light having thegreen hue, which is emitted by the display device 136 and viewed throughthe electrochromic element 134 when the electrochromic medium 126 is inapproximately the low transmittance state. When considering lines 212,214, and 216, with respect to FIG. 11, the color perceived by the usermaintains the green hue even as the transmittance state of theelectrochromic medium 126 is altered between the high and lowtransmittance states. Thus, a change in h_(ab) between lines 212 and 216is a value (approximately twenty-five degrees (25°)) that remainsapproximately representative of light having the green hue, rather thanhaving a larger change in h_(ab), such that the perceived light nolonger has a green hue.

Typically, the reduced change in h_(ab) as the transmittance state isaltered is independent of a C* value. In further regards to FIG. 11,lines 200, 202, 204, 206, 208, 210, 212, 214, and 216 illustrates thehue (angle) in addition to a chroma (i.e., the length of the line).

According to one embodiment, primaries emitted by the display device 136can include at least one red primary, one green primary, and one blueprimary light. Typically, the display device 136 can be configured toemit one primary or combine two or more primaries to emit light ofanother color. Alternatively, the primaries can include at least onered, at least one green, at least one blue, and at least one yellow. Thedisplay device 136 can be configured as a white light source withvariable filters (e.g., typical LCD), or can have a plurality of lightsources 140 that emit light at various wavelengths, as described above.

With continued reference to the L* a* b* color space, the display device136 can be configured to emit at least a first primary and a secondprimary. The first and second primaries, as viewed through theelectrochromic medium 126 in an approximately the high transmittancestate (e.g., a first hue h_(ab)), in approximately the low transmittancestate (e.g., a second hue h_(ab)′), and all intermediate transmittancestates exhibit a change in h_(ab) (Δh_(ab)) (e.g., a change in the firstand second hues) of less than approximately thirty one degrees (31°).

The change in h_(ab) between approximately the high transmittance stateand approximately the low transmittance state for both the first andsecond primaries can be less than approximately twenty-five degrees(25°), according to one embodiment. However, the change in h_(ab)between approximately the high and low transmittance states for both thefirst and second primaries can be less than approximately fifteendegrees (15°). Typically, the first and secondary primaries havedifferent hues, such as, but not limited to, the first primary beinglight having a red hue and the second primary being light having a greenhue (FIG. 13). In such an embodiment, the change in h_(ab) betweenapproximately the high and low transmittance states for light having ared hue can range from approximately twenty-three degrees (23°) toapproximately thirteen degrees (13°), and the change in h_(ab) for lighthaving a green hue can range from approximately thirty-one degrees (31°)to approximately fourteen degrees (14°) (FIGS. 17A and 17B).

The display device 136 can be further configured to emit a thirdprimary, wherein a change in h_(ab) of the third primary between whenthe electrochromic medium 126 is in approximately the high transmittancestate (e.g., a first hue h_(ab)) and in approximately the lowtransmittance state (e.g., a second hue h_(ab)′) can be less thanapproximately forty-one degrees (41°). Alternatively, the change inh_(ab) of the third primary can be less than approximately thirty-fivedegrees (35°), the change in h_(ab) of the third primary can be lessthan approximately twenty degrees (20°), or the change in h_(ab) of thethird primary can be less than approximately ten degrees (10°).According to one embodiment, the third primary can be a different colorthan the first and second primaries, such as, but not limited to, lighthaving a blue hue (FIG. 13). In such an embodiment, the change in h_(ab)for light having a blue hue can range from approximately forty-onedegrees (41°) to approximately zero degrees (0°) (FIGS. 17A and 17B).

Additionally and alternatively, the display device 136 can be configuredto emit a fourth primary. In such an embodiment, a change in h_(ab) ofthe fourth primary when the electrochromic medium 126 is inapproximately the high transmittance state and in approximately the lowtransmittance state can be less than approximately fifty-five degrees(55°). It should be appreciated that additional primaries beyond four,or alternative primaries, can be used in a manner as taught herein forembodiments in which such an approach would be advantageous.

Alternatively, the change in h_(ab) between approximately the high andlow transmittance states for the fourth primary can be less thanapproximately fifty degrees (50°), the change in h_(ab) for the fourthprimary can be less than approximately forty degrees (40°), or thechange in h_(ab) for the fourth primary can be less than approximatelythirty degrees (30°). A further alternative can be wherein thedifferences in h_(ab) for the fourth primary can be less thanapproximately fifteen degrees (15°).

Typically, the fourth and any additional primaries are different colors,such as, but not limited to, the fourth primary being light having ayellow hue (FIG. 13). As described above, hues other than those of theprimaries can be obtained by mixing of two or more primaries. In thismanner, a yellow hue can be obtained, for example, by the mixing of redand green primaries at a suitable ratio. An amber hue can also beobtained by the mixing of primaries, for example red and green in aratio slightly different than that for yellow. In such an embodiment,the change in h_(ab) between the approximately high and approximatelylow transmittance states for light having a yellow hue can range fromapproximately fifty-five degrees (55°) to approximately twenty-sevendegrees (27°), and the change in h_(ab), between the approximately highand approximately low transmittance states for light having an amber huecan range from approximately fifty-five degrees (55°) to approximatelynine degrees (9°) (FIGS. 17A and 17B).

According to one embodiment, the rear view mirror 110 can include theelectro-optic device having the front element 112 that includes thefirst and second surfaces 112 a, 112 b, the rear element 114 having athird and fourth surfaces 114 a, 114 b, and the electro-optic medium 126in optical communication between the front element 112 and the rearelement 114, wherein the electro-optic medium 126 can be configured todynamically adjust between a high transmittance state and a lowtransmittance state. The rear view mirror 110 can further include thedisplay device 136 in optical communication with the electro-opticdevice. The display device 136 can include the at least one light source100, and the display device 136 can be configured to emit at least afirst primary and a second primary. The first and second primaries caneach have a first hue (h_(ab)) when viewed through the electro-opticelement 134 in approximately the high transmittance state and a secondhue (h_(ab)′) when viewed through the electro-optic element 134 inapproximately the low transmittance state, wherein a change in the firstand second hues ((h_(ab)) is less than approximately thirty-one degrees(31°).

Another exemplary illustration in reduced color change is illustrated inFIGS. 15A and 15B, which shows color change in the Y_(u′,v′) colorspace. The Y_(u′,v′) color space is a color space adopted by CIE in 1976as transformation of the 1931 CIE Y_(x,y) color space, but whichattempted perceptual uniformity. The insert triangle may represent aportion of the u′,v′ color space addressable by the display device 136(i.e., the color gamut), which illustrates the subset of colorcapability of a particular embodiment of a RGB display. This chartillustrates the color changes of emitted light having a plurality ofhues as the electrochromic medium 126 is altered between the hightransmittance state and the low transmittance state. The magnitude ofcolor changes of a prior art electrochromic medium may be consideredless desirable by the viewer.

The lines of FIG. 15A directly compare the change in color for anembodiment of the present invention described in Example 12 with thechange in color of a prior art configuration described in Example 1,wherein a display element of the display device 136 is viewed throughthe electrochromic element 134, while the electrochromic medium 126 isin various transmittance states. Line 218 represents a display elementhaving a red color of a prior art system at various transmittance statesof the electrochromic system, and line 220 represents a display elementhaving a red color in accordance with one embodiment of the presentinvention at various transmittance states. According to one embodiment,a display element can emit light, such as, but not limited to, andindicator light, a symbol, text, and image, emitted light viewed throughone or more pixels, the like, or a combination thereof.

Line 222 represents a display element having a green color of a priorart system at various transmittance states of the electrochromic system,and line 224 represents a display element having a green color inaccordance with one embodiment of the present invention at varioustransmittance states of the electrochromic system. Line 226 represents adisplay element having a blue color of a prior art system at varioustransmittance states of the electrochromic system 138, and line 228represents a display element having a blue color in accordance with oneembodiment of the present invention at various transmittance states ofthe electrochromic system 138. As shown in FIG. 15, line 228 maintainsthe blue color, whereas line 226 extends towards a green region of theu′,v′ color space, and thus, illustrates an undesirable color change fora prior art system shown by line 226 compared to a system of the presentinvention as shown by line 228.

With continued reference to FIG. 15A, line 230 represents a displayelement having a yellow color of a prior art system at varioustransmittance states of the electrochromic system, and line 232represents a display element having a yellow color in accordance withone embodiment of the present invention at various transmittance statesof the electrochromic system 138. Line 232 maintains the yellow color,whereas line 230 extends towards a green region of the u′,v′ colorspace, and thus, illustrates an undesirable color change for a prior artsystem shown by line 230 compared to a system of the present inventionas shown by line 232. Line 234 represents a display element having aamber color of a prior art system at various transmittance states of theelectrochromic system 138, and line 236 represents a display elementhaving an amber color in accordance with one embodiment of the presentinvention at various transmittance states of the electrochromic system138. Line 236 maintains the amber color, whereas the line 234 extendstowards a green region of the u′,v′ color space, and thus, illustratesan undesirable color change for a prior art system shown by line 234compared to a system of the present invention as shown by line 236. Line238 represents a display element having a white color of a prior artsystem at various transmittance states of the electrochromic system, andline 240 represents a display element having a white color in accordancewith one embodiment of the present invention at various transmittancestates of the electrochromic system 138. As shown by the comparison oflines in FIG. 15A, the perceived color change of the emitted light isreduced as compared to the prior art. Thus, lines 220, 224, 228, 232,236, and 240 remain closer to their respective starting point (the pointwhere the electrochromic system 138 is in its approximately hightransmittance state) for each respective color, and remain closer to thestarting color as the electrochromic system 138 changes from its hightransmittance state to its low transmittance state, as compared to theprior art lines 218, 222, 226, 230, 234, and 238, which illustrate anundesirable color change in the prior art.

Continuing to reference the u′,v′ color space and FIG. 15B, the firstand second primaries viewed through the electrochromic medium 126 inapproximately the high transmittance state and in approximately the lowtransmittance state exhibit a change in color (ΔE_(u′,v′)) of less thanapproximately 0.06. The color change, ΔE_(u′,v′), for both the first andsecond primaries can be less than approximately 0.05, according to oneembodiment. However, the color change, ΔE_(u′,v′), for both the firstand second primaries can be less than approximately 0.04. Typically, thefirst and second primaries have different colors, such as, but notlimited to, the first primary being light having a red color and thesecond primary being light having a green color (FIG. 15A).

The display device 136 can be further configured to emit a thirdprimary, wherein a color change, ΔE_(u′,v′), of the third primary whenthe electrochromic medium 126 is in approximately the high transmittancestate and in approximately the low transmittance state is less thanapproximately 0.08. Alternatively, the color change, ΔE_(u′,v′), of thethird primary can be less than approximately 0.07, the color change,ΔE_(u′,v′), of the third primary can be approximately 0.06, or the colorchange, ΔE_(u′,v′), of the third primary can be less than approximately0.05. According to one embodiment, the third primary can be a differentcolor than the first and second primaries, such as, but not limited to,light having a blue color (FIG. 15A).

The display device 136 can be configured to emit a fourth primary,according to one embodiment. In such an embodiment, a color change,ΔE_(u′,v′), of the fourth primary when the electrochromic medium 126 isin approximately the high transmittance state and in approximately thelow transmittance state is less than approximately 0.08, a color change,ΔE_(u′,v′), of light having an amber color when the electrochromicmedium 126 is in approximately the high transmittance state and inapproximately the low transmittance state can be less than approximately0.09, or a combination thereof.

Alternatively, the color change, ΔE_(u′,v′), for at least one of thefourth and any additional primaries can be less than approximately 0.08,a color change, ΔE_(u′,v′), for at least one of the fourth and anyadditional primaries can be less than approximately 0.07, a colorchange, ΔE_(u′,v′), for at least one of the fourth and any additionalprimaries can be less than approximately 0.06, or a color change,ΔE_(u′,v′), for at least one of the fourth and any additional primariescan be less than approximately 0.05. Accordingly to one embodiment, thefourth primary can be light having a yellow hue.

For purposes of explanation and not limitation, in operation, theelectrochromic system 138 can be configured to emit light via thedisplay device 136 through the layers of the electrochromic element 134to display an image to the user or occupant of the motor vehicle.Further, the electrochromic system 138 can be configured to display thisimage in a manner viewable by the user without regard as to thetransmittance states of the electrochromic medium 126, and thus, anychange in the perceived color of the displayed image is reduced, eventhough the transmittance level of the electrochromic medium 126 is beingaltered. The color change, ΔE_(u′,v′), of the image viewed by the useris reduced even as the transmittance states of the electrochromic medium126 is being altered, such that, in a non-limiting example, an imagethat appears yellow when the electrochromic medium 126 is in the hightransmittance state does not appear green when the electrochromic medium126 is in the low transmittance state.

In another embodiment, the color accuracy can be based upon lightemitted from the display device 136 that is viewed through theelectrochromic element 134 having a plurality of primary colors, ascompared to a broadband source, such as daylight (e.g., Illuminat D₆₅ orIlluminat A). Thus, coatings of the front and rear elements 112, 114,components of the electrochromic medium 126, active control of thedisplay device 136, or a combination thereof can be adapted tocompensate for adverse attenuation affects the electrochromic medium 126has on the light viewed there through at various transmittance states.As described above, the display device 136 can be configured to at leastpartially compensate for adverse attenuation of the emitted light byother components of the electrochromic system 138. When the displaydevice 136 is configured to at least partially enhance the coloraccuracy (e.g., reduce a perceived color change), the display device 136can be an LCD, wherein the backlighting source(s) and/or the filters(e.g., RGB, RGB-Yellow) are adapted to at least partially compensate fora color change that is a result of the emitted light viewed through theelectrochromic medium 126. Thus, the LCD can be enhanced to give coloraccuracy to two or more primaries. This tuning might include, but notlimited to, modifying the instructions in video driver circuitry and/orprogramming to actively or passively compensate for the same colorshift.

The backlighting and display filter of the display device 136, theattenuation of the emitted light viewed through the electrochromicmedium 134, or a combination thereof, can affect color balance of theperceived light. Additionally or alternatively, an intensity and/orcolor of a backlighting light source of the display device 136 (e.g.,RGB light source, white phosphor light source, etc.) can be configuredto actively or passively compensate for attenuation of the emitted lightviewed through the electrochromic medium 126. The backlighting of thedisplay device 136 can be, but is not limited to, direct lighting oredge lighting.

A magnitude of perceived color change can be approximately inverselyproportional to a width of a color filter (e.g., full width/half max ofthe light distribution band) of the display device 136 (e.g., thedisplay device 136 being a LCD), according to one embodiment. Typically,the width of the filter can correspond to the range of wavelengths thatpass through the filter. Thus, if the backlight is monochromic, therecan be substantially no shift in color and the filter can onlyattenuate. However, when the backlight of the display device 136 isconfigured to emit a plurality of primary colors, a wide filter in aparticular wavelength range can be utilized in the display device 136,which can allow for greater intensity, but reduced color accuracy, ornarrow filters in a particular wavelength range can be utilized in thedisplay device 136, which can allow for reduced intensity, but increasedcolor accuracy. Typically, LCDs have opted for greater intensity andreduced color accuracy. In this case, if the prior art electrochromicmedium is used, there may be primaries that shift colors as theelectrochromic medium shifts from high transmittance to lowtransmittance. However, even with the prior art electrochromic medium,the adverse effect the electrochromic medium may have on the lightviewed there through may, at least partially, be compensated for bydynamically controlling how the light is emitted from the display device136.

According to one embodiment, using an RGB video display (e.g., thedisplay device 136) behind the electrochromic element 134 can compensatefor adverse attenuation of the emitted light by adjusting a relativeintensity of the red, green, and blue emitters in order to maintainbetter color rendering. For example, in the case of transmission thatwas greater for the blue region of the spectrum and lesser for the redregion it may be desirable to decrease the intensity of the blue emitterand increase the intensity of the red emitter. This type of adjustmentcan be appropriate in this and other designs whether the spectral biasof the transmission is a gentle slope or one with more distance bands oftransmission.

When the display device 136 is intended for use when the mirror elementis dimmed, intensity adjustments may be made to compensate for anyspectral bias from the coatings and, of, the activated electrochromicmedium 126. The intensity adjustment may be a function of the operatingvoltage of the electrochromic system 138, and/or other feedbackmechanism to match the relative RGB intensities appropriately for agiven point in the color excursion of the electrochromic element 134.

Optionally because tolerances of electrochromic element 134 constructioncan include, but are not limited to, cell spacing, sheet resistances ofcoatings, and drive circuit components, it can be difficult to determineprecisely the point on the color excursion curve a device will be basedon a look up table with respect to a voltage. Also, because theelectrochromic element 134 can attain the low transmittance state atlower temperatures at a lesser voltage than when at a highertemperature, the characteristic of voltage may not adequately define theposition on a color excursion curve for a particular device. Forexample, the outside electrochromic mirror 111 a, 111 b may be operatingat a temperature that is sufficiently different than an inside mirror110 to place it on a different location on the color excursion curve fora given voltage. In addition some components of the electrochromicmedium 126 experience a shift in their spectral absorptioncharacteristics with temperature. So, depending on the color accuracyrequired for a particular display application in various transmittancestates, methods other than a voltage look up table may assist someembodiments to perform more optimally. A look up table containing bothelement voltage and current draw data, may, in some embodiments providea more accurate sense of the transmitted color of the element. Acircuit, such as those described in U.S. Pat. No. 6,222,177, entitled“ELECTROCHROMIC ELEMENT DRIVER WITH A NEGATIVE OUTPUT RESISTANCE,” theentire reference hereby being incorporated herein by reference, mayalso, in some embodiments, improve the accuracy of any adjustments to adisplay.

With respect to FIGS. 21 and 22, according to one embodiment, methodsusing an additional sensor 276 behind the electrochromic element 134facing the rear of the vehicle can be used for attaining an accuratereading. If a glare sensor is in an electrochromic system 138 outside ofthe darkening region, such as the “chin” of an inside mirror 110assembly, looking through a partially transmissive reflective ringbezel, or is in the bezel, another sensor just inside the darkeningregion can receive light from the same glare sources. When the twosignals are compared, the degree of attenuation of the signal betweenthe sources can, via a lookup table, or other algorithm, yield theposition on a color excursion curve that would translate into anintensity adjustment of the colors in a display, such as an RGB displayor other combinatorial color display. In another embodiment, areflective region such as a dot can be placed on the first or secondsurface of an electrochromic system 138, and a signal is emitted throughthe electrochromic element 134 from the rear of the electrochromicelement 134 and the reflected signal measured. Based on the attenuationof that signal, the degree of dimming of the display device 136 can, andtherefore its position on a color excursion curve, can be determinedand, again, adjustments to the display device 136 can be made. The lightsignal reflected by the dot could be of a single spectral makeup, or itcould be pulsed between signals of different make ups. If an RGB displaywere being adjusted, it could in some embodiments be advantageous toquickly pulse between at least one red light, at least one blue light,and at least one green light for the signal to the reflector of similarspectral characteristics used in the display device 136, and adjust theRGB display based on the relative attenuation detected between thosesignals.

When used as an inside rearview mirror, the inside mirror assembly 110can exhibit a high end reflectance of at least about sixty percent (60%)while also exhibiting a transmittance of at least five percent (5%) andat least the area in front of the display device 136, according to oneembodiment. The display device 136 can be an LCD that, together with theelectrochromic element 134 can be configured to provide a luminositywhen viewed through the electrochromic element 134 of at least about twohundred fifty candelas per meter squared (250 cd/m²). Alternatively,depending upon the requirements, suitable luminosity can be at leastabout four hundred candelas per meter squared (400 cd/m²), at leastabout five hundred candelas per meter squared (500 cd/m²), at leastabout six hundred candelas per meter squared (600 cd/m²), at least aboutseven hundred candelas per meter squared (700 cd/m²), at least about onethousand candelas per meter squared (1,000 cd/m²), at least about onethousand five hundred candelas per meter squared (1,500 cd/m²), at leastabout two thousand seven hundred fifty candelas per meter squared (2,750cd/m²), at least about thirty-five hundred candelas per meter squared(3,500 cd/m²), at least about five thousand candelas per meter squared(5,000 cd/m²), and at least about eight thousand candelas per metersquared (8,000 cd/m²).

Referring again to FIGS. 7A-7H, the coatings of the third surface 114 acan be sealably bonded to the coatings on the second surface 112 b in aspaced-apart and parallel relationship by a seal member 116 disposednear the outer perimeter of both second surface 112 b and third surface114 a. Seal member 116 may be any material that is capable of adhesivelybonding the coatings on the second surface 112 b to the coatings on thethird surface 114 a to seal the perimeter such that electrochromicmaterial 126 does not leak from chamber 125. Optionally, the layer oftransparent conductive coating 128 and the layer of reflector/electrode120 may be removed over a portion where the seal member is disposed(typically not the entire portion, otherwise the drive potential couldnot be applied to the two coatings). In such a case, seal member 116 cantypically bond well to glass.

The performance requirements for a perimeter seal member 116 used in anelectrochromic system 138 are similar to those for a perimeter seal usedin an LCD. The seal should have good adhesion to glass, metals and metaloxides; can have low permeabilities for oxygen, moisture vapor, andother detrimental vapors and gases; and cannot interact with or poisonthe electrochromic or liquid crystal material it is meant to contain andprotect. The perimeter seal can be applied by means commonly used in theLCD industry, such as by silk-screening or dispensing. Totally hermeticseals, such as those made with glass frit or solder glass, can be used,but the high temperatures involved in processing (usually near fourhundred fifty degrees (450° C.)) this type of seal can cause numerousproblems, such as glass substrate warpage, changes in the properties oftransparent conductive electrode, and oxidation or degradation of thereflector. Because of their lower processing temperatures,thermoplastic, thermosetting, or UV curing organic sealing resins can beused. Because of their excellent adhesion to glass, low oxygenpermeability and good solvent resistance, epoxy-based organic sealingresins can be used. These epoxy resin seals may be UV curing, orthermally curing, such as with mixtures of liquid epoxy resin withliquid polyamide resin or dicyandiamide, or they can be homopolymerized.The epoxy resin may contain fillers or thickeners to reduce flow andshrinkage such as fumed silica, silica, mica, clay, calcium carbonate,alumina, etc., and/or pigments to add color. Fillers pretreated withhydrophobic or silane surface treatments can be used. Cured resincrosslink density can be controlled by use of mixtures ofmono-functional, di-functional, and multi-functional epoxy resins andcuring agents. Additives such as silanes or titanates can be used toimprove the seal's hydrolytic stability, and spacers such as glass beadsor rods can be used to control final seal thickness and substratespacing. Suitable epoxy resins for use in a perimeter seal member 116include, but are not limited to: “EPON RESIN” 813, 825, 826, 828, 830,834, 862, 1001F, 1002F, 2012, DPS-155, 164, 1031, 1074, 58005, 58006,58034, 58901, 871, 872, and DPL-862 available from Shell Chemical Co.,Houston, Tex.; “ARALITE” GY 6010, GY 6020, CY 9579, GT 7071, XU 248, EPN1139, EPN 1138, PY 307, ECN 1235, ECN 1273, ECN 1280, MT 0163, MY 720,MY 0500, MY 0510, and PT 810 available from Ciba Geigy, Hawthorne, N.Y.;and “D.E.R.” 331, 317, 361, 383, 661, 662, 667, 732, 736, “D.E.N.” 431,438, 439 and 444 available from Dow Chemical Co., Midland, Mich.Suitable epoxy curing agents include V-15, V-25, and V-40 polyamidesfrom Shell Chemical Co.; “AJICURE” PN-23, PN-34, and VDH available fromAjinomoto Co., Tokyo, Japan; “CUREZOL” AMZ, 2MZ, 2E4MZ, C11Z, C17Z, 2PZ,2IZ, and 2P4MZ available from Shikoku Fine Chemicals, Tokyo, Japan;“ERISYS” DDA or DDA accelerated with U-405, 24EMI, U-410, and U-415available from CVC Specialty Chemicals, Maple Shade, N.J.; and “AMICURE”PACM, 352, CG, CG-325, and CG-1200 available from Air Products,Allentown, Pa. Suitable fillers include fumed silica such as “CAB-O-SIL”L-90, LM-130, LM-5, PTG, M-5, MS-7, MS-55, TS-720, HS-5, and EH-5available from Cabot Corporation, Tuscola, Ill.; “AEROSIL” R972, R974,R805, R812, R812 S, R202, US204, and US206 available from Degussa,Akron, Ohio. Suitable clay fillers include BUCA, CATALPO, ASP NC,SATINTONE 5, SATINTONE SP-33, TRANSLINK 37, TRANSLINK 77, TRANSLINK 445,and TRANSLINK 555 available from Engelhard Corporation, Edison, N.J.Suitable silica fillers are SILCRON G-130, G-300, G-100-T, and G-100available from SCM Chemicals, Baltimore, Md. Suitable silane couplingagents to improve the seal's hydrolytic stability are Z-6020, Z-6030,Z-6032, Z-6040, Z-6075, and Z-6076 available from Dow CorningCorporation, Midland, Mich. Suitable precision glass microbead spacersare available in an assortment of sizes from Duke Scientific, Palo Alto,Calif.

The layer of a transparent electrically conductive material 128 can bedeposited on the second surface 112 b to act as an electrode.Transparent conductive material 128 may be any material which bonds wellto front element 112, is resistant to corrosion to any materials withinthe electrochromic system 138, resistant to corrosion by the atmosphere,has minimal diffuse or specular reflectance, high light transmission,near neutral coloration, and good electrical conductance. Transparentconductive material 128 may be fluorine-doped tin oxide, doped zincoxide, indium zinc oxide (Zn₃In₂O₆), indium tin oxide (ITO),ITO/metal/ITO (IMI) as disclosed in “Transparent ConductiveMultilayer-Systems for FPD Applications,” by J. Stollenwerk, B. Ocker,K.H. Kretschmer of LEYBOLD AG, Alzenau, Germany, the materials describedin above-referenced U.S. Pat. No. 5,202,787, such as TEC 20 or TEC 15,available from Libbey Owens-Ford Co. of Toledo, Ohio, or othertransparent conductors. Exemplary electrochromic systems are describedin U.S. Pat. No. 7,688,495, entitled “THIN-FILM COATINGS, ELECTRO-OPTICELEMENTS AND ASSEMBLIES INCORPORATING THESE ELEMENTS,” U.S. PatentApplication Publication No. 2008/0302657, entitled “METHOD AND APPARATUSFOR ION MILLING,” U.S. Patent Application Publication No. 2007/0201122,entitled “THIN-FILM COATINGS, ELECTRO-OPTIC ELEMENTS AND ASSEMBLIESINCORPORATING THESE ELEMENTS,” and U.S. patent application Ser. No.12,691,830, entitled “IMPROVED THIN-FILM COATINGS, ELECTRO-OPTICELEMENTS AND ASSEMBLIES INCORPORATING THESE ELEMENTS,” the entirereferences hereby being incorporated herein by reference.

Generally, the conductance of transparent conductive material 128 willdepend on its thickness and composition. IMI generally has superiorconductivity compared with the other materials. Exemplary IMIs aredescribed in U.S. Patent Application Publication No. 2007/0206263,entitled “ELECTRO-OPTICAL ELEMENT INCLUDING IMI COATINGS,” the entirereference hereby incorporated herein by reference. IMI is, however,known to undergo more rapid environmental degradation and suffer frominterlayer delamination. The thickness of the various layers in the IMIstructure may vary, but generally the thickness of the first ITO layerranges from about 10 Å to about 200 Å, the metal ranges from about 10 Åto about 200 Å, and the second layer of ITO ranges from about 10 Å toabout 200 Å. If desired, an optional layer or layers of a colorsuppression material 130 may be deposited between transparent conductivematerial 128 and the second surface 112 b to suppress the reflection ofany unwanted portions of the electromagnetic spectrum. According to oneembodiment, half-ware ITO having a thickness of approximately 1450 Å, oreighty percent (80%) ITO having a thickness of approximately 1150 Å canbe utilized.

Examples of electrochromic systems, display devices, and/or mirrors andcomponents thereof are described in Canadian Patent No. 1,300,945,entitled “AUTOMATIC REARVIEW MIRROR SYSTEM FOR AUTOMOTIVE VEHICLES,”U.S. Pat. No. 6,700,692, entitled “ELECTROCHROMIC REARVIEW MIRRORASSEMBLY INCORPORATING A DISPLAY/SIGNAL LIGHT,” U.S. Pat. No. 5,940,201,entitled “ELECTROCHROMIC MIRROR WITH TWO THIN GLASS ELEMENTS AND AGELLED ELECTROCHROMIC MEDIUM,” U.S. Pat. No. 5,928,572, entitled“ELECTROCHROMIC LAYER AND DEVICES COMPRISING SAME,” U.S. Pat. No.5,434,407, entitled “AUTOMATIC REARVIEW MIRROR INCORPORATING LIGHTPIPE,” U.S. Pat. No. 5,448,397, entitled “OUTSIDE AUTOMATIC REARVIEWMIRROR FOR AUTOMOTIVE VEHICLES,” U.S. Pat. No. 6,157,480, entitled “SEALFOR ELECTROCHROMIC DEVICES,” U.S. Pat. No. 6,170,956, entitled “REARVIEWMIRROR WITH DISPLAY,” U.S. Pat. No. 5,808,778, entitled “ELECTRO-OPTICREARVIEW MIRROR FOR AUTOMOTIVE VEHICLES,” U.S. Pat. No. 6,356,376,entitled “ELECTROCHROMIC REARVIEW MIRROR INCORPORATING A THIRD SURFACEMETAL REFLECTOR AND A DISPLAY/SIGNAL LIGHT,” U.S. Pat. No. 6,512,624,entitled “ELECTROCHROMIC REARVIEW MIRROR INCORPORATING A THIRD SURFACEPARTIALLY TRANSMISSIVE REFLECTOR,” U.S. Pat. No. 7,009,751, entitled“ELECTROCHROMIC REARVIEW MIRROR INCORPORATING A THIRD SURFACE PARTIALLYTRANSMISSIVE REFLECTOR,” U.S. Pat. No. 6,870,656, entitled“ELECTROCHROMIC REARVIEW MIRROR ELEMENT INCORPORATING A THIRD SURFACEREFLECTOR,” U.S. Pat. No. 7,209,277, entitled “ELECTROCHROMIC REARVIEWMIRROR INCORPORATING A THIRD SURFACE REFLECTOR WITH AT LEAST ONEGRAPHICAL INDICIA,” U.S. Pat. No. 7,417,781, entitled “ELECTROCHROMICREARVIEW MIRROR INCORPORATING A THIRD SURFACE REFLECTOR,” U.S. Pat. No.6,020,987, entitled “ELECTROCHROMIC MEDIUM CAPABLE OF PRODUCNIG APRE-SELECTED COLOR,” U.S. Patent Application Publication No.2009/0296190, entitled “REARVIEW MIRROR ASSEMBLIES WITH ANISOTROPICPOLYMER LAMINATES,” U.S. Pat. No. 4,902,108, entitled“SINGLE-COMPARTMENT, SELF-ERASING, SOLUTION-PHASE ELECTROCHROMICDEVICES, SOLUTIONS FOR USE THEREIN, AND USES THEREOF,” U.S. Pat. No.5,128,799, entitled “VARIABLE REFLECTANCE MOTOR VEHICLE MIRROR,” U.S.Pat. No. 5,278,693, entitled, “TINTED SOLUTION-PHASE ELECTROCHROMICDEVICES,” U.S. Pat. No. 5,280,380, entitled “UV-STABILIZED COMPOSITIONSAND METHODS,” U.S. Pat. No. 5,282,077, entitled “VARIABLE REFLECTANCEMIRROR,” U.S. Pat. No. 5,294,376, entitled “FINISHER FOR AN IMAGEFORMING APPARATUS,” U.S. Pat. No. 5,336,448, entitled “ELECTROCHROMICDEVICES WITH BIPYRIDINIUM SALT SOLUTIONS,” U.S. Pat. No. 5,818,625,entitled “DIMMABLE REARVIEW MIRROR INCORPORATING A THIRD SURFACE METALREFLECTOR,” U.S. Pat. No. 6,441,943, entitled “INDICATORS ANDILLUMINATORS USING A SEMICONDUCTOR RADIATION EMITTER PACKAGE,” U.S. Pat.No. 6,521,916, entitled “RADIATION EMITTER DEVICES AND METHOD OF MAKINGTHE SAME,” and U.S. Pat. No. 6,020,987, entitled “ELECTROCHROMIC MEDIUMCAPABLE OF PRODUCING A PRE-SELECTED COLOR,” the entire references herebybeing incorporated herein by reference.

Typically, thin silver or silver alloy layers are higher in blue-greentransmission and lower in blue-green light reflection which imparts ayellow hue to the reflected image. For purposes of explanation and notlimitation, a 2000 Å ITO underlayer of approximately ¾ wave in thicknesscan supplement the reflection of blue-green light which results in amore neutral hue in reflection. Other odd quarter wave multiples (e.g.,¼, 5/4, 7/4, etc.) can also be effective in reducing reflected hue. Itshould be noted that other transparent coatings, such as (F)SnO or(AL)ZnO, or a combination of dielectric, semi-conductive, or conductivecoatings, can be used to supplement blue-green reflection and produce amore neutral reflected hue in the same manner.

Referring to FIG. 3 for one embodiment of the present invention, areflector/electrode that is made from a single layer of a reflectivesilver or silver alloy 121 is provided that is in contact with at leastone solution-phase electrochromic material. The layer of silver orsilver alloy covers at least part of the entire third surface 114 a ofsecond element 114. The reflective silver alloy means a homogeneous ornon-homogeneous mixture of silver and one or more metals, or anunsaturated, saturated, or supersaturated solid solution of silver andone or more metals. The thickness of reflective layer 121 ranges fromabout 50 Å to about 2000 Å, or from about 200 Å to about 1000 Å. Ifreflective layer 121 is disposed directly to the glass surface, theglass surface can be treated by plasma discharge to improve adhesion.Examples of coatings and electrochromic systems are described in U.S.Pat. No. 7,746,534, entitled “THIN-FILM COATINGS, ELECTRO-OPTIC ELEMENTSAND ASSEMBLIES INCORPORATING THESE ELEMENTS,” the entire referencehereby being incorporated herein by reference.

In another embodiment, the reflector/electrode 120 shown in FIG. 4 hasat least two layers (121 and 122), where at least one layer of a basematerial 122 covers substantially the entire portion of the thirdsurface 114 a and at least one layer of a reflective material 121 coversthe inner section of the third surface 114 a, but does not cover theperipheral edge portion 125 where seal member 116 is disposed.Peripheral portion 125 may be created by masking that portion of layer122 during deposition of the layer of reflective material 121, or thelayer of reflective material may be deposited over the entire thirdsurface and subsequently removed or partially removed in the peripheralportion. The masking of layer 122 may be accomplished by use of aphysical mask or through other well-known techniques, such asphotolithography and the like. Alternatively, layer 122 may be partiallyremoved in the peripheral portion by a variety of techniques, such as,for example, by etching (laser, chemical, or otherwise), mechanicalscraping, sandblasting, or otherwise. Laser etching can be used becauseof its accuracy, speed, and control. Partial removal is preferablyaccomplished by laser etching in a pattern where enough metal is removedto allow the seal member 116 to bond directly to the third surface 114 awhile leaving enough metal in this area such that the conductance inthis area is not significantly reduced.

In addition, an optional intermediate layer of a conductive material 123may be placed over the entire area of third surface 114 a and disposedbetween the reflective layer 121 and the base layer 122, or it may beplaced only under the area covered by layer 121, (e.g., not inperipheral edge portion 125). If this optional intermediate layer isutilized, it can cover the entire area of third surface 114 a or it maybe masked or removed from the peripheral edge portion as discussedabove.

An optional flash over-coat layer 124 may be coated over the reflectivelayer 121. The reflective layer 121, the optional intermediate layer123, and the base layer 122 can have properties similar to thatdescribed herein, except that the layer of reflective material 121 neednot bond well to the epoxy seal, since it is removed in the peripheralportion where the seal member 116 is placed. Because the interactionwith the epoxy seal is removed, silver metal itself, in addition to thealloys of silver described herein, will function as the reflectivelayer. Alternatively, an adhesion promoter can be added to the sealingmaterial which enhances adhesion to silver or silver alloys and thereflective layer can be deposited over most of the third surfaceincluding substantial portions under the seal area. Such adhesionpromoters are disclosed in U.S. Pat. No. 6,157,480, entitled “IMPROVEDSEAL FOR ELECTROCHROMIC DEVICES,” the entire reference hereby beingincorporated herein by reference.

Referring now to FIGS. 5A and 5B, an improved mechanism for applying adrive potential to the layer of transparent conductive material 128 isshown. Electrical connection between the power supply and the layer oftransparent conductive material 128 is made by connecting the buss bars(or clips 119 a) to the area of reflector/electrode 120 a, such that thedrive potential travels through the area of reflector/electrode 120 aand conductive particles 116 b in sealing member 116 before reaching thetransparent conductor 128. The reflector/electrode must not be presentin area 120 c, so that there is no chance of current flow fromreflector/electrode area 120 a to 120 b. This configuration isadvantageous in that it allows connection to the transparent conductivematerial 128 nearly all the way around the circumference, and thereforeimproves the speed of dimming and clearing of the electrochromic media126.

In such a configuration, sealing member 116 comprises a typical sealingmaterial, (e.g., epoxy 116 a, with conductive particles 116 b containedtherein). The conductive particles may be small, such as, for example,gold, silver, copper, etc., coated plastic with a diameter ranging fromabout 5 microns to about 80 microns, in which case there should be asufficient number of particles to ensure sufficient conductivity betweenthe reflector/electrode area 120 a and the transparent conductivematerial 128. Alternatively, the conductive particles may be largeenough to act as spacers, such as, for example, gold, silver, copper,etc., coated glass or plastic beads. The reflector/electrode 120 isseparated into two distinct reflector/electrode areas (120 a and 120 b,separated by an area 120 c devoid of reflector/electrode). There aremany methods of removing the reflector/electrode 120 from area 120 c,such as, for example, chemical etching, laser ablating, physical removalby scraping, etc. Deposition in area 120 c can also be avoided by use ofa mask during deposition of reflector/electrode. Sealing member 116 withparticles 116 b contacts area 120 a such that there is a conductive pathbetween reflector/electrode area 120 a and the layer of transparentconductive material 128. Thus, electrical connection to thereflector/electrode area 120 b that imparts a potential to theelectrochromic medium is connected through clips 119 b to the electroniccircuitry at reflector/electrode area 120 d (FIG. 5B). No conductiveparticles 116 b can be placed in this reflector/electrode area 120 bbecause of the possibility of an electrical short betweenreflector/electrode area 120 b and the layer of transparent conductivematerial 128. If such an electrical short occurred, the electrochromicsystem 138 would not operate properly. Additionally, no conductive seal116 b should be present in area 120 b.

Layer 121 may be made of any of the reflective materials described aboveand can be made of silver or a silver alloy. The thickness of reflectivelayer 121 in the arrangement shown in FIG. 7A can be between 30 Å and800 Å. The thickness of layer 121 will depend on the desired reflectanceand transmittance properties. For an inside rearview mirror, layer 121can have a reflectance of at least sixty percent (60%) and atransmittance through window 146 of ten percent (10%) to fifty percent(50%). For an outside mirror, the reflectance can be above thirty-fivepercent (35%) and the transmittance can be approximately ten percent(10%) to fifteen percent (15%), and/or at least twenty percent (20%) forthose regions that are in front of one of the lights of a signal light.

Window 146 in layer 121 may be formed by masking window area 146 duringthe application of the reflective material. At this same time, theperipheral region of the third surface 114 a may also be masked so as toprevent materials such as silver or silver alloy (when used as thereflective material) from being deposited in areas to which seal 116must adhere, so as to create a stronger bond between seal 116 andcoating 172 or element 114. Additionally, an area in front of sensor 160(FIG. 2) may also be masked.

The masking of window 146 in layer 121 may be a discrete mask such thatnone of the material of layer 121 is deposited within window area 146,or a gradient mask may be utilized, which gradually reduces the amountof the material of layer 121 from the periphery of window 146 to itscenter. The extent of the gradient masking may vary considerably suchthat virtually none of the material of layer 121 is provided over muchof the display area of window 146 with just gradient edges surroundingwindow 146 to a configuration whereby all of window 146 is covered withat least some portion of the material of layer 121. Alternativeconstructions are illustrated in FIGS. 6, 7B-7H, 8, and 9A-9G. It shouldbe noted that the optical constants of materials vary somewhat withdeposition method and conditions employed. These differences can have asubstantial effect on the actual optical values and optimum thicknessesused to attain a value for a given coating stack.

Another embodiment is illustrated in FIG. 35, wherein the electrochromicdevice 138 (e.g., a multi-zone mirror element) can be structured with astack 278 having an upper reflecting layer 284, the thickness of whichis not substantially uniform but rather slightly variable. In thefollowing description, therefore, a reference is made to elements of thegeneral thin-film structure of the embodiment of the electrochromicelement 134, as illustrated in FIG. 35, and the differences in thin-filmstructure are emphasized. The electrochromic element 134, as illustratedin FIG. 35, can also include a supporting base 286, which has a baselayer 288, an ITO layer 290, an opaque region 292, a transflectiveregion 294, and a transition region 296.

The properties of the stack are summarized in the table of FIG. 36 as afunction of a one-dimensional position (corresponding to the y-axis ofFIG. 35) along the third surface 114 a of the electrochromic element134. The electrochromic element 134 can include three metallic layersthat change in thickness, which can be positioned across the thirdsurface 114 a. Such metallic layers can include, but are not limited to,a layer of Chromium 280, a layer of Ruthenium 282, and a layer of silveralloy 284. The essentially opaque area can be seen to extendapproximately between the positions identified as −0.75 in and 5 inacross the substrate. The transflective display area, extendingapproximately between the positions of −5 in and 1.75 in, utilizes onlythree of the five layers listed in table of FIG. 36. In this embodiment,the graded Chromium opacifying layer 280, deposited on the supportingbase that can include a glass substrate and a base bi-layer of TiO₂ andITO, asymptotically extends into the transflective display area. A flashopacifying layer 282 of Ruthenium, deposited above the Chromium layer280, extends asymptotically into the transflective display area beyondthe extent of the Chromium layer 280. The fairly complicated thicknessprofile of an upper continuous reflecting layer 284 of silver alloyassures a substantially linear change in reflectance between the opaquearea and display area.

Yet another alternative embodiment represents a modification of theelectrochromic system 138 of FIG. 35 by employing a non-uniformreflective layer 284. Such an embodiment may generally achieve anapproximately uniform reflectance in excess of at least fifty percent(50%) across the surface of the mirror element and a transmittancelevels below approximately five percent (5%) in the opaque area andbelow approximately fifty percent (50%) in the transflective area. In aspecific embodiment, an approximately uniform reflectance of aboutsixty-five percent (65%) across the surface of the mirror element may beachieved, while simultaneously keeping transmittance level well below ahalf percent (0.5%) in the opaque area and above twenty percent (20%) inthe transflective area. The geometry of thin-film layers comprising athin-film stack that may be deposited on the third surface to achievesuch properties, as described in the table of FIG. 37.

With respect to FIG. 38, another exemplary embodiment of theelectrochromic system 138 is illustrated. In such an embodiment, atleast one of the front element 112 and the rear element 114 can includean approximately 1.6 mm glass substrate. A TiO₂ layer 298 can beapproximately 144 Å thick, and an ITO layer 300 can be approximately 180Å thick. A silver alloy layer 302 can be approximately 240 Å thick, andadditionally or alternatively, include approximately seven percent (7%)gold. The cell spacing filled with the electrochromic medium 126 can beapproximately 160 microns, and the ITO layer 304 can be approximately1450 Å thick. An appliqué layer 306 can be on the fourth surface 114 b.Various exemplary characteristics of the electrochromic system 138 aredescribed in the table of FIG. 39.

By way of explanation and not limitation, the electrochromic medium 126can include at least one solvent, at least one anodic electroactivematerial, and at least one cathodic electroactive material. One or moreof the solvent, the anodic electroactive material, and the cathodicelectroactive material can be adapted to reduce a perceived color changeof light viewed there through (e.g., be approximately neutral). Examplesof such electrochromic mediums are described in U.S. Patent ApplicationPublication No. 2010/0073754, entitled “ULTRAVIOLET LIGHT STABILIZINGCOMPOUNDS AND ASSOCIATED MEDIA AND DEVICES,” U.S. Pat. No. 7,428,091,entitled “SEMICONDUCTOR DEVICE HAVING DELAY DRIFT COMPENSATION CIRCUITTHAT COMPENSATES FOR DELAY DRIFT CAUSED BY TEMPERATURE AND VOLTAGEVARIATIONS IN CLOCK TREE,” and U.S. Pat. No. 7,256,924, entitled“MULTI-CELL ELECTROCHROMIC DEVICES,” the entire references hereby beingincorporated herein by reference. Other examples are discussed in U.S.Pat. No. 6,141,137, entitled “ELECTROCHROMIC MEDIA FOR PRODUCING APRESELECTED COLOR,” and U.S. Pat. No. 6,037,471, entitled“ELECTROCHROMIC COMPOUNDS,” the entire references hereby beingincorporated herein by reference.

As described above, the components of the electrochromic element 134 canbe selected to reduce adverse attenuation effects of the electrochromicmedium 126 in various transmittance states. For purposes of explanationand not limitation, the below Examples 1-17, referenced in the tables ofFIGS. 17A and 17B, describe various electrochromic solutions, which canbe adapted to at least partially reduce a perceived color change oflight viewed through the electrochromic element 134, as described above.

Example #1 Prior Art

In a flask, under a nitrogen purge, is added 567.5 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 16.3 milligrams of1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3 milligrams ofTINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:10 2(hydroxy)-ethylmethacrylate: methacrylate copolymer, 0.24 milligrams of dibutyl tindiacetate and 41 grams of propylene carbonate. This solution is stirredand heated at 85° C. for 2 hours to dissolve. To a second flask, that isbeing purged with nitrogen, is added 1,779.8 milligrams of1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate, 20.6 milligramsof 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocinium tetrafluoroborate,180 milligrams of LUPRANATE™ (BASF) and 58 grams of propylene carbonate.This solution is stirred at room temperature to dissolve. The solutionsare combined and mixed thoroughly. This solution is de-gassed undervacuum and then 137 micron transflective mirror elements arevacuum-filled with this solution. These mirror elements are heated to85° C. for 2 hours to cure the polyurethane gel and then are wired to avariable voltage power supply. LED backlighting is placed behind theelements and they are then darkened at various potentials and colormeasurements are taken. The construction of the electrochromictransflective mirror element, configured with LED backlighting, forExamples 1-13, is described below.

Example #2

In a flask, under a nitrogen purge, is added 510.7 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 132.3 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,779.8milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #3

In a flask, under a nitrogen purge, is added 499.4 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 158.8 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,779.8milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tretrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #4

In a flask, under a nitrogen purge, is added 499.4 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 158.8 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,779.8milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #5

In a flask, under a nitrogen purge, is added 521.6 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 105.8 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,779.8milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #6

In a flask, under a nitrogen purge, is added 533.0 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 79.4 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,779.8milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #7

In a flask, under a nitrogen purge, is added 437.2 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 254.8 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1724.2milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #8

In a flask, under a nitrogen purge, is added 382.6 milligrams of5,10-dimethyl-5,10-dihydrophenazine, 382.2 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1724.2milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #9

In a flask, under a nitrogen purge, is added 685.8 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 181.3 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1646.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #10

In a flask, under a nitrogen purge, is added 563.5 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 367.5 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1646.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,20.6 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #11

In a flask, under a nitrogen purge, is added 563.5 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 367.5 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1646.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,41.2 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #12

In a flask, under a nitrogen purge, is added 586.0 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 382.2 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1629.6milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,82.4 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #13

In a flask, under a nitrogen purge, is added 1,339.5 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 509.6 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 32.6milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 1354.7milligrams of TINUVIN 384™ (Ciba Geigy), 35.2 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.48 milligramsof dibutyl tin diacetate and 82 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 3259.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,165.2 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 360 milligrams of LUPRANATE™ (BASF) and 116 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transfiective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #14

In a flask, under a nitrogen purge, is added 1,172.1 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 764.4 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 32.6milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 1354.7milligrams of TINUVIN 384™ (Ciba Geigy), 35.2 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.48 milligramsof dibutyl tin diacetate and 82 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 3259.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,165.2 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 360 milligrams of LUPRANATE™ (BASF) and 116 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken. The construction of the electrochromic transflective mirrorelement, configured with LED backlighting, for Examples 14-16, isdescribed below.

Example #15

In a flask, under a nitrogen purge, is added 1,339.5 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 509.6 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 32.6milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 1354.7milligrams of TINUVIN 384™ (Ciba Geigy), 35.2 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.48 milligramsof dibutyl tin diacetate and 82 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 3259.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,165.2 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 360 milligrams of LUPRANATE™ (BASF) and 116 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #16

In a flask, under a nitrogen purge, is added 1,255.8 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 637.0 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 32.6milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 1354.7milligrams of TINUVIN 384™ (Ciba Geigy), 35.2 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.48 milligramsof dibutyl tin diacetate and 82 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 3259.3milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,165.2 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 360 milligrams of LUPRANATE™ (BASF) and 116 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken.

Example #17

In a flask, under a nitrogen purge, is added 608.5 milligrams of5,10-dineopentyl-5,10-dihydrophenazine, 396.9 milligrams of5,10-dineopentyl-5,10-dihydro-2,7-[2-(ethyl)hexyl]phenazine, 16.3milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrocene, 677.3milligrams of TINUVIN 384™ (Ciba Geigy), 17.6 grams of 1:102(hydroxy)-ethyl methacrylate: methacrylate copolymer, 0.24 milligramsof dibutyl tin diacetate and 41 grams of propylene carbonate. Thissolution is stirred and heated at 85° C. for 2 hours to dissolve. To asecond flask, that is being purged with nitrogen, is added 1,668.6milligrams of 1,1′-di(octyl)-4,4′-dipyridinium bis tetrafluoroborate,82.4 milligrams of 1,1′,2,2′,3,3′,4,4′,5,5′-decamethyl ferrociniumtetrafluoroborate, 180 milligrams of LUPRANATE™ (BASF) and 58 grams ofpropylene carbonate. This solution is stirred at room temperature todissolve. The solutions are combined and mixed thoroughly. This solutionis de-gassed under vacuum and then 137 micron transflective mirrorelements are vacuum-filled with this solution. These mirror elements areheated to 85° C. for 2 hours to cure the polyurethane gel and then arewired to a variable voltage power supply. The transmittance of thedevices is altered at various potentials and color measurements aretaken. The construction of the electrochromic transflective mirrorelement, configured with LED backlighting, for Example 17, is describedbelow.

For the above Examples 1-13 electrochromic cells were constructed asfollows. A layer of ITO of approximately 145 nm thickness was depositedon sheets of approximately 1.6 mm soda lime float glass prior to beingcut to the shape of an inside automotive mirror. Layers of TiO₂ ofapproximately 45 nm and ITO of approximately 22 nm were successivelydeposited forming a bi-layer on sheets of 1.6 mm soda lime float glassprior to being cut to the shape of an inside automotive mirror. On thepieces of glass having the coatings of TiO₂ and ITO, additional coatingswere deposited having a somewhat complicated profile as described below.Onto the TiO₂/ITO bi-layer, a layer of chrome was deposited. This layerhad a thickness of approximately 50 nm outside of the region in front ofthe display device and was not deposited in front of the display device.Onto the chrome layer and additional layer of ruthenium was deposited.This layer had a thickness of approximately 5.0 nm outside the region infront of the display and was not deposited in front of the displaydevice. Next, a layer of silver/gold alloy (93% silver/7% gold) wasdeposited. This layer had a thickness of approximately 9 nm outside theregion in front of the display device and a thickness of approximately16 nm in front of the display device. In addition, there was a gradientto the layers of chrome, ruthenium, and silver/gold alloy between theareas in front of the display device and away from the display devicesuch that the reflectance difference between the two areas are notreadily discernable to an observer. The techniques for obtaining agradient with good aesthetic transition are in accordance with theteachings of U.S. Patent Application Publication No. 2009/0207513,entitled, “MULTI-ZONE MIRRORS.” Reference can also be made to FIGS. 35and 36 and the accompanying text. On the ITO coated side of the piece ofglass (i.e., surface two in the completed element), a bead of epoxycontaining spacers was deposited, this was laid up onto the second piecesuch that the coated surfaces face one another (i.e., the reflectivesurface would be the third surface of the electrochromic element) and sothat an opening remained to facilitate the vacuum fill of theelectrochromic medium, such that there remained an offset between theglass pieces allowing for electrical connection. The epoxy was cured andthe elements were then filled with the electrochromic medium (fluid/gel)systems described in Examples 1-13 and plugged with a UV cured material.

For the above Examples 14-16 electrochromic cells were constructed asfollows. A layer of ITO of approximately 115 nm thickness was depositedon sheets of approximately 1.6 mm soda lime float glass prior being cutto the shape of an inside automotive mirror. Layers of TiO₂ ofapproximately 45 nm and ITO of approximately 22 nm were successivelydeposited forming a bi-layer on separate sheets of 1.6 mm soda limefloat glass prior to being cut to the shape of an inside automotivemirror. On the piece of glass having the coatings of TiO₂/ITO bi-layeran additional coating of silver/gold alloy (93% silver/7% gold) wasdeposited to a thickness of approximately 23 nm. Onto the ITO coatedside of the piece of glass (i.e., surface two in the completed element),a bead of epoxy containing spacers was deposited, this was laid up tothe second piece such that the reflective surfaces faced one another(i.e., the reflective surface would be the third surface of theelectrochromic element) and so that an opening remained to facilitatethe vacuum fill of electrochromic medium and such there remained anoffset between the glass pieces allowing for electrical connection. Theepoxy was cured and the elements were then vacuum backfilled with theelectrochromic medium (fluid/gel) systems described in Examples 14-16and plugged with a UV cured material.

For the above Example 17 electrochromic assembly was constructed asfollows. A layer of ITO of approximately 115 nm was deposited on sheetsof approximately 1.6 mm soda lime float glass prior to being cut to theshape of an inside automotive mirror. Onto the ITO coated side of one ofthe pieces of glass (i.e., surface two of the completed element), a beadof epoxy containing spacers was deposited, this was laid up onto thesecond similar piece so that the coated surfaces faced one another andso that there was an opening remained to facilitate the vacuum fill ofthe electrochromic medium, such that there remained an offset betweenthe glass pieces allowing for electrical connection. The epoxy was curedand the element was then vacuum backfilled with the electrochromicmedium (fluid/gel) system described in Example 17 and plugged with a UVcured material. An anisotropic polymer film “DBEF-Q” available from 3Mcorporation was also cut to mirror shape. The DBEF-Q film was thenlaminated (i.e., at approximately 105° C. at approximately 190 psig)between the electrochromic element described above and an approximately1.1 mm piece of soda lime glass cut to the shape of an inside mirror inaccordance with teachings found in U.S. Patent Application PublicationNo. 2010/0110553, entitled “REARVIEW MIRROR ASSEMBLIES WITH ANISOTROPICPOLYMER LAMINATES,” the entire reference hereby being incorporatedherein by reference. This additional glass had coatings on the surfacethat is in contact with the DBEF-Q film. The coating deposited on theglass surface was a layer of TiO₂ of approximately 55 nm and a layer ofITO of approximately 5 nm was deposited onto the layer of TiO₂ forming abi-layer. A layer of chrome of approximately 50 nm was deposited ontothe TiO₂/ITO bi-layer in the areas that are not in front of the displaydevice. This layer of chrome has a graded thickness in the area aroundthe display. The DBEF-Q film was oriented such that its polarization ofhigh transmittance was lined up with the polarization of the displaydevice in accordance with teachings found in the above-referenced U.S.Patent Application Publication No. 2010/0110553.

Photopic measurements wherein described were taken with equipment knowncommonly in the industry as MacBeth Color Eye 7000A Spectrophotometer,Ocean Optics USB 4000 Spectro radiometer and Photo Research PR-705Spectro radiometer. The Photopic instrument incident angle is orientatedperpendicular to the mirror front surface at normal zero degrees (0°)horizontal, zero degrees (0°) vertical of a distance approximatelyfourteen inches (14 in) away from the front surface of the mirror.Individual colors were produced with standard LED light source NICHIA™NSSW064A shined through the display LTA035B3J1F which is fully driven incolor modes red, green, blue, amber, and yellow. LTA035B3J1F is anormally white Active Matrix TFT display and the white state isconsidered non-driven from the display point of view.

The above embodiments and examples are particularly well suited forprimaries that have relatively broad widths. Many displays are oftenconstructed with light sources and liquid crystals optimized for highbrightness. As stated above this generally requires that the red, green,and blue primaries have a relatively wide bandwidth to maximize thelight transmittance. When coupled with a white light source thisapproach can lead to displays with high light intensity levels. Thetrade-off is lower color accuracy of the display due to the wide bandwidths of the primaries. The electrochromic chemistry discussed anddefined above with respect to the electrochromic element providesrelatively uniform light attenuation during the darkening excursions(e.g., lowering the transmittance state) of the electrochromic media.This allows the electrochromic system to maintain color accuracy in thehigh transmittance, low transmittance, and the intermediate states.

FIG. 23 illustrates the transmittance of the electrochromic system 138with various applied potentials. The 0.0 V curve is the hightransmittance case while the 1.2 V curve is the low transmittance state.The intermediate states are noted with the applied potentials (i.e., the0.5 V curve, the 0.6 V curve, the 0.7 V curve, and the 0.8 V curve). Thedata of FIG. 23 was simulated using thin film models. The electrochromicelement 134 was modeled with two 1.6 mm thick pieces of glass. The ITOlayer on the second surface 112 b was 145 nm thick (½ wave), thetransflective electrode on the third surface 114 a has a 45 nm TiO₂layer directly on the glass, an 18 nm ITO layer on the TiO₂ layer and a25 nm silver gold alloy layer on the ITO layer. The electrochromic modelwas set at 190 microns and the optical constants of the fluid arecomparable to the prior art reference in Example 1 above. As shown inFIG. 23, the transmittance spectra has varying transmittance versuswavelength at the different applied potentials. The non-equivalenttransmittance spectra result in non-uniform modulation of the RGBprimaries resulting in color shifts, as discussed in detail herein.

As can be seen from FIG. 23, it does not appear that dual or moreprimaries can be selected that will maintain color accuracy since thechange in transmittance with applied potential changes dramatically withwavelength. However, in accordance with an embodiment of the presentinvention, an alternate approach to broad primaries is to use narrowprimaries. Some types of LEDs provide a narrow wavelength distribution.For the examples below the wavelength bandwidth for the primaries wasset to 5 nm or less full width half max. It should be appreciated thatalternate wavelength bandwidths are possible. The exemplary color belowis in the u′,v′ system with an approximately 10 degree observer.

The use of narrow primaries is not a universal solution. For theelectrochromic system 138 having the characteristics of FIG. 23, we havedetermined that only a very narrow set of primary combinations canpreserve color accuracy during the darkening excursion for anelectrochromic system 138 or other electro-optic system. The table ofFIG. 24 and the chart of FIG. 25 illustrate the color ΔE_(u′,v′) valuesbetween the high transmittance states and the intermediate states. Theprimary pairs or triplets in this example are a sample of the possibleprimary combinations wavelength pairs. These are meant to berepresentative of the high ΔE_(u′,v′) values that will arise with randompairings of primaries.

A method was developed to determine viable primaries whose relativeintensities do not change to a large extent during the darkeningexcursion. The ratio of intensities of potential primary pairs can becalculated for the high and low transmittance states and then compared.By way of explanation and not limitation, the intensity ratio wascalculated for 400 nm to every wavelength from 401 nm to 675 nm for eachnanometer wavelength. The calculations were then repeated for 405, 410,. . . 500 nm instead of the 400 nm primary. FIGS. 26 and 27 (sameinformation on different vertical scales) show the calculated differencein intensities for the high and low transmittance states. Suitableprimaries are obtained when the difference is approximately zero.

As can be determined from FIGS. 26 and 27, the vast majority ofpotential primary pairs have intensity ratio differences that arerelatively high. In order to have relatively low ΔE_(u′,v′) values overthe darkening excursion, the difference in the intensity ratios can beless than 0.75. Alternatively, the differences in the intensity ratiocan be less than 0.50 or less than 0.25. It can be beneficial to selectprimary pairs wherein the intensity ratio differences are near zero. Forthis condition the primary pairs are most stable and will be more robustin practice.

FIG. 28 shows the color for optimal primary pairs and triplets whosecolor is stable over the darkening excursion of the electrochromicmedium 126. Pairs 405/565, 405/630, 460/550, 460/635 and triplets405/565/630 and 460/550/635 exhibit small ΔE_(u′,v′) values over thedarkening excursion. The table of FIG. 29 shows the ΔE_(u′,v′) valuesfor these primary combinations.

The color gamut for the 460/550/635 triplet is shown in FIG. 30. Thetriangle defines the attainable colors possible with this primarysystem. The dots (or “x”) represent colors attained by adjusting theintensity levels of the primaries. The table of FIG. 31 illustrates therelative intensities of the primaries, an average ΔE_(u′,v′), and themaximum ΔE_(u′,v′) for the points shown in FIG. 30.

The color stability for this technique can be dependent on thetransmittance characteristics of the electrochromic medium 126 and thewidth of the primaries. Depending on the transmittance spectra versusapplied potential one or more primary combinations may be viable for agiven system.

Additionally or alternatively, the coatings or stacks of theelectrochromic element 134 can be configurable to compensate for theadverse affects on color rendering that are caused by the light viewedthrough other components of the electrochromic element 134. Exemplarycoating stacks are described in U.S. Provisional Patent Application Ser.No. 60/779,369, entitled “COATINGS AND REARVIEW ELEMENTS INCORPORATINGTHE COATINGS,” U.S. Provisional Patent Application Ser. No. 60/810,921,entitled “ELECTROCHROMIC REARVIEW MIRROR ASSEMBLY INCORPORATING ADISPLAY/SIGNAL LIGHT,” and U.S. Provisional Patent Application Ser. No.60/888,686, entitled “ELECTRO-OPTIC ELEMENT WITH IMPROVED TRANSPARENTCONDUCTOR,” the entire references hereby incorporated herein byreference.

One exemplary stack can have a reflectance of approximately sixtypercent to sixty-five percent (60%-65%), a transmittance ofapproximately twenty percent to twenty-five percent (20%-25%) and anon-opaque coating, such that a bright display device can be in optimalcommunication behind the rear element 114 without utilizing a hard mask.The exemplary stack can have a display zone with a reduced reflectanceto increase transmittance, and an opaque appliqué. Another exemplarystack has a transflective region and a non-transflective, hard maskedregion. Yet another exemplary state has a reflectance display zone ofapproximately sixty-five percent (65%) and a non-display, opaque area.

To increase the dynamic range, a control circuit constructed inaccordance with the present invention utilizes two or more differentcurrent ranges for driving the LED display depending upon whethernighttime or daytime conditions are present. An exemplary controlcircuit for performing this function is shown in FIG. 18. Asillustrated, the circuit includes a control circuit 900, which mayinclude a microprocessor also functioning as an inside mirror controlcircuits, which is coupled to an ambient light sensor 932, a glaresensor 934, and an electrochromic element 920 having a constructionsimilar to those disclosed above. Thus, control circuit 900 may performvarious control functions for controlling the reflectivity ofelectrochromic mirror element 920 in response to light levels sensed byambient sensor 932 and glare sensor 934.

One of the purposes of the circuit shown in FIG. 18 is to control thebrightness of one or more LEDs 902 of an indicator, signal light, ordisplay. In general, the brightness of light emitted from an LED is afunction of the current flowing through the LED. Control circuit 900controls the amount of current flowing through LED 902 by generating apulse-width modulated signal 904 that is provided through a resistor 906to the base of a current-sourcing transistor 908. The source oftransistor 908 is coupled to LED 902 and the drain is coupled to groundvia a resistor 910. The drain of transistor 908 is selectively coupledto ground via another current path through a resistor 912 and aswitching transistor 914. The resistance of second resistor 912 ispreferably significantly less than the resistance of resistor 910 suchthat when switching transistor 914 is conducting, the amount of currentflowing through sourcing transistor 908 and LED 902 is significantlyincreased. The conducting status of switching transistor 914 iscontrolled in accordance with a day/night signal 916 issued from controlcircuit 900 and supplied to the base of transistor 914 via a resistor918.

Although the above-described circuit is utilized for controlling one ormore LEDs of a display, a similar arrangement may be configured forcontrolling the brightness of various other forms of displays that maybe utilized within a rearview mirror assembly or other vehicleaccessory.

The various embodiments of the electrochromic medium 126 of the presentinvention taught above enable neutral and stable color in the hightransmittance state, the low transmittance state, and the intermediatestates for transmitted light. In some embodiments it may also beneficialfor the electrochromic system 138 to have neutral reflected color in thehigh reflectance state, the low reflectance state, and the intermediatestates. The neutral reflected color provides a desirable aestheticappearance of the mirror as well as rendering the true colors of theobjects in the reflected images. As described above, the electrochromicsystem 138 can be configured to reduce a perceived color change oftransmitted light as the electrochromic medium 126 alters betweentransmittance states. Generally, the reflected light can be ambientlight that is light other than the light emitted from the display device136. The electrochromic system 138 can also be configured to reduce aperceived color change of reflected light as the electrochromic medium126 alters between transmittance states.

The reflected color is based on the summation of the reflectance of thelight at each optical interface in the electrochromic system 138. Eachsurface of the glass is an optical interface. The reflectance at eachsurface is determined by the refractive index of the incident media, therefractive index of the exit media, and any coating present on thesurfaces. For the first surface 112 a, the incident media is air, andthe exit media is the substrate, (i.e., glass and typically no coatingsare present). For the second surface 112 b, the incident media is glass,the exit media is the electrochromic medium 126, and there may becoatings present, such as ITO or an IMI stack. The third surface 114 ahas the electrochromic medium 126 as the incident media, the glass asthe exit media, and in some embodiments, the transflective reflectorelectrode. The fourth surface 114 b typically has glass as the incidentmedia, air as the exit media, and no coatings. In other embodiments, thefirst surface 112 a and fourth surface 114 b may have one or morecoatings present, or the third surface 114 a can have a transparentelectrode and the transflective coating may be present on the fourthsurface 114 b. The reflectance at each interface will vary withproperties of the bounding media and any coatings present. The lightfrom each interface adds together for each wavelength and the resultantspectrum determines the intensity of the light and the color.

When the electrochromic element 134 is in the high transmittance andreflectance state, the reflectance spectrum can be typically dominatedby the reflectance of the transflector coating. In intermediatetransmittance or reflectance states the reflectance can be dominated bythe light from different interfaces depending on the specific absorptionproperties of the electrochromic medium 126. When the electrochromicelement 134 is in approximately the fully low transmittance state, witha minor contribution of light from the reflector on either the thirdsurface 114 a or the fourth surface 114 b reaching the observer, theappearance of the electrochromic system 138 is due mainly to acombination of light from the first and second surfaces 112 a, 112 b ofthe front substrate 112. With no coating on the first surface 112 a,about four percent (4%) reflectance of relative uniform intensity acrossthe visible spectrum from the uncoated glass interface is obtained.Reflected color is therefore primarily due to thin film interferenceeffects from the transparent electrode on the second surface 112 b.

The reflected color of the transparent conducting oxide or transparentelectrode (IMI) on the second surface 112 b, in one embodiment, can bedue primarily from the thickness of the layer. As the thickness of theTCO is increased, the color changes. The color can be further altered byadding additional layers either above or below the TCO. A portion of theabove referenced patents teach methods for reducing the color of TCO andother coatings. Materials used for transparent second surface conductiveelectrodes are typically materials with an approximately 1.8 index ofrefraction, or greater. The color impact of these conductive electrodematerials can be reduced by using half wave thickness multiples, usingthe thinnest layer possible (or a layer with reduced thickness) for theapplication or by the use of one of several “non-iridescent glassstructures.” Non-iridescent structures will typically use either a highand low index layer under the conductive coating (see, for example, U.S.Pat. No. 4,377,613, entitled “NON-IRIDESCENT GLASS STRUCTURES,” and U.S.Pat. No. 4,419,386, entitled “NON-IRIDESCENT GLASS STRUCTURES,”), or anintermediate index layer (see U.S. Pat. No. 4,308,316, entitled“NON-IRIDESCENT GLASS STRUCTURES,” or U.S. Pat. No. 5,395,698, entitled“NEUTRAL, LOW EMISSIVITY COATED GLASS ARTICLES AND METHOD FOR MAKING,”)or graded index layer (see U.S. Pat. No. 4,440,822, entitled“NON-IRIDESCENT GLASS STRUCTURES”) to reduce color impact. IMItransparent electrodes are also referenced in a portion of the abovereferenced patents, wherein the reflected color in the dark state andhow to alter it is addressed.

As noted above, the reflectance of the electrochromic element 134 in thelow transmittance state is affected by the thickness of the TCO andwhether other layers are present in the coating stack. As a result ofthe absorption in ITOs or other TCOs being fairly low, there is littlecolor change in the bright state of the mirror due to thickness changesin the layer. Similarly, in a window, the ITO does not contributesubstantially to the transmitted color nor is color tuning by adjustingthe ITO a primary option for altering the reflected or transmittedcolor. In other embodiments, the absorption or transmittancecharacteristics of the TCO or IMI coating may be adjusted or tuned tospecifically help address a deficiency due to the characteristics ofanother component, as discussed in greater detail herein.

Another design attribute desirable in some embodiments of theelectrochromic system 138 is to have a very low reflectance in the lowtransmittance state as well as a neutral color. This can result in anincreased or maximum dynamic range for the mirror elements. The table ofFIG. 34A depicts the dark state reflectance values, color, and C* valuesfor the electrochromic device 138 as a function of the ITO thicknesscalculated using thin film models. In this example, the electrochromicmedium 126 is set to be substantially opaque. When the electrochromicmedium 126 is not completely opaque, the reflected light from the mirrorcoating can add to the reflectance in FIG. 34A. As depicted, the lowtransmittance state reflectance can reach a minimum at about 140 to 150nm or a ½ wave coating with a design wavelength of 550 nm. As thethickness deviates from this half wave thickness, the low transmittancestate reflectance rises and the dynamic range decreases. The reflectedcolor varies with the thickness of the ITO coating. The C* values varyalso with the thickness. The most neutral color happens with a thicknessless than that of a common half wave thickness (130 nm versus 150 nm).

An exemplary illustration of reflected color change of theelectrochromic system 138 is illustrated in FIG. 16A, which correspondsto Example 14 with neutral chemistry and that includes an approximately130 nm thickness ITO coating on the second surface 112 b. This curveillustrates the perceived color change as the electrochromic medium 126is altered from approximately the high transmittance state toapproximately the low transmittance state. The curves remainingproximate the origin with a low C* value through the darkening curve anda particularly low C* value in the fully low transmittance state. Thiscan be compared to the prior art curves illustrated in FIG. 16B whichcorresponds to Example 1 with the prior art electrochromic medium and a150 nm ITO coating on the second surface. FIG. 16B has an increasedperceived color change of the reflected light when the electrochromicmedium is altering between the high transmittance state and the lowtransmittance state relative to FIG. 16A. The C* of the reflected lightfor the electrochromic system 138 can be less than approximately twenty(20), at one or more of the reflectance and/or transmittance states.Alternatively, the C* of the reflected light for the electrochromicsystem 138 can be less than approximately fifteen (15), or less thanapproximately ten (10) at one or more of the reflectance and/ortransmittance states. Thus, the reflective components of theelectrochromic element 134 can be substantially color neutral.

The above example demonstrates that the thickness of a singletransparent conducting oxide layer (e.g., ITO) can be selected to have abeneficial effect on the reflected color of the electrochromic system138. The following examples in Table 34B were calculated using thin filmmodels. The optical constants of an electrochromic medium similar toExample 14 were used, which corresponds to an approximately fully opaquefluid. The optical contributions from the reflector electrode aretherefore eliminated and do not contribute to the reflected color.Examples of three different coating stacks (color suppression) toprovide neutral reflected color are presented. In each case the ITOthickness is at 149 nm, but the use of the various color suppressiontechniques work equally well for other thicknesses of ITO or othertransparent conducting oxides.

In other embodiments, it may be advantageous to have a reflectance inthe low reflectance state higher than that demonstrated by thatattainable by the ITO layer within the thickness ranges described above.The electrochromic element 134 may be operated with applied potentialvalues that do not allow the electrochromic medium 126 to attain itsfully opaque state or the cell spacing of the electrochromic element 134may be altered such that some desired level of reflectance from thereflector is obtained. Alternately, as described above, the transparentelectrode stack comprising an IMI, a TCO layer, or the like may bemodified to adjust the low end reflectance value. In particular, anadditional layer or layers may be placed above or below the ITO or theTCO layer. In the table of FIG. 33 a single layer is placed below theITO layer at a quarter wave thickness. It should be appreciated by otherthicknesses may be chosen as needed without deviating from the spirit ofthe invention. The reflectance increases with increasing refractiveindex values. In other embodiments it may be advantageous to bothincrease the low end reflectance and have a relatively neutral color inthe low reflectance state. In the table of FIG. 34B it is illustratedthat for the different three layer stacks, the low end reflectance isaltered while maintaining a neutral reflected color.

By way of explanation and not limitation, the electrochromic system 138can be used as an auto-dimming rearview mirror in a motor vehicle.Alternatively, the electrochromic system 138 can be used as a dimmingmirror in other environments. In an exemplary embodiment of a motorvehicle, the electrochromic system 138 can be configured to dim as afunction of ambient and glare light. Further, the display device 136 canbe configured to emit light (e.g., the one or more primaries projectingthe display element), such as, but not limited to, text, symbol, orimage in a plurality of colors while the electrochromic element 134 isin any transmittance state. Thus, the display device 136 can beconfigured to emit light to project images associated with warningsystems, navigational systems, or other suitable systems integrated withthe motor vehicle. The reduced perceived color change of the emittedlight by a user as the transmittance state of the electrochromic medium126 alters can be advantageous, so that the plurality of colors emittedby the display device 136 that can form the text, the image, and/or thesymbols can be perceived approximately the same by the user withoutregard to the transmittance state of the electrochromic medium 126.Thus, the electrochromic medium 126, chamber 125, and other elements ofthe electrochromic element 134 can extend over the display device 136,and the electrochromic medium 126 does not have to be in a hightransmittance state when the display device 136 is emitting light to theuser.

By integrating a personal computer with a telematics system such as thatdisclosed in U.S. Pat. No. 6,980,092, entitled “VEHICLE REARVIEW MIRRORASSEMBLY INCORPORATING A COMMUNICATION SYSTEM,” of which the entirereference is hereby incorporated herein by reference, the computermonitor may be used for displaying various forms of informationincluding e-mail messages and pages, turning indicators for navigationalsystems; service reminders based on speed and mileage; vehicle heading;school, hospital zone warnings, weather, traffic, and emergency vehiclewarnings; night vision displays; advertisements; stock quotes; and otherinformation. Textual messages and other alphanumeric data and/or symbolsmay be superimposed over the video images displayed on the displaydevice. If the vehicle is equipped with appropriate rear vision cameras,such as disclosed and described in U.S. patent application Ser. No.09/001,855, entitled “VEHICLE VISION SYSTEM,” and U.S. Pat. No.6,550,949, entitled “SYSTEMS AND COMPONENTS FOR ENHANCING REAR VISIONFROM A VEHICLE,” the entire references hereby being incorporated hereinby reference, coupling such cameras to the display device 136 wouldallow a video display of a view at the rear of the vehicle to assistdrivers while connecting the vehicle to a trailer and for proportionalsteering with respect to the trailer. Other graphics relating to theconnection of the vehicle to a trailer may also be displayed.

It should be appreciated by those skilled in the art that embodimentsdescribed herein that include a display can also be applied with equalefficacy to imaging embodiments. For display embodiments, the system isconfigured to substantially maintain color accuracy for the RGB (orother) color primaries emitted by a display behind the electro-opticdevice as it darkens or brightens (e.g., clears). For imagingembodiments, the direction of the light is reversed; however, thefunction of the electro-optic device to reduce alteration of colorprimaries is substantially identical (FIG. 42). An example of usingelectrochromic devices as variable optical density filters and variableapertures is disclosed in U.S. Pat. No. 6,963,437, entitled “DEVICESINCORPORATING ELECTROCHROMIC ELEMENTS AND OPTICAL SENSORS,” which ishereby incorporated herein by reference. Most imaging devices usestandard RGB filters to divide incoming light into primaries compatiblewith digital encoding. The human eye, equivalently, breaks light intothree primaries for the case of color vision based on the cone receptorsin the retina. The rods, responsible for black and white vision,function more as color insensitive densitometers.

In one embodiment, an imaging sensor can be behind the electro-opticdevice such as, but not limited to, a transflective, electrochromicmirror. Such a device can be configured to be used for in cabin imagingof a vehicle for safety features such as, but not limited to,determining occupancy of the vehicle, attentiveness of the driver,sleepy driver detection, the like, or a combination thereof. It can bedesirable for the color of the image captured by the sensor not tochange significantly as the electrochromic mirror darkens to reduceglare.

In another embodiment, a variable attenuator can be in front of animaging sensor in order to reduce saturation of the device by high lightlevels. The variable attenuator can be configured to function as aneutral density filter in that the action of the device would vary thelight intensity at the sensor without changing the relative ratio of theprimaries to each other. Thus, the action of the electro-optic basedattenuator can be configured to reduce a shift of the color of theimage. This embodiment could also be applied to eye glasses. Thus, thetint of the glasses can be electronically controlled in order to controlthe intensity of light passing through the lenses. In this example, asbefore, the device can be configured to reduce the color shift caused bydarkening of the electro-optic device in order to maintain coloraccuracy when viewing the environment through the glasses. Suchelectronically dimmable eye glasses could function simply as variabletint sunglasses or this function could be applied to more advancedapplications such as the so-called “augmented reality” glasses.Augmented reality glasses superimpose an electronically generated(display) image on top of the image of the environment viewed by theuser similar to a head-up display in a car or aircraft. For thisapplication, the control of environmental light intensity reaching theeye could be electronically attenuated in order to maintain adequatebrightness and contrast of the electronically displayed image beingoverlaid on the user's view. The electro-optic device can be configuredso the attenuation of the light does not substantially cause colorshift.

The action of a variable attenuator might be substantially uniformacross its field of view as is the case for the neutral density filterdescribed above or it might be non-uniform. An example of a non-uniformattenuator is an irising filter that can be configured to function as avariable aperture for imaging. To generate an irising effect the outerperimeter of the variable attenuator can darken faster than the centralzone. This can be controlled in several ways. A higher potential can beapplied to the perimeter zones relative to the central zone. This canmean discrete bands of controlled potential or a potential gradientbetween the perimeter and the center of the EC cell (FIG. 43A).Alternatively, controlling cell spacing in the electro-optic device suchthat the central zones have smaller cell spacing than the outer zonescan be used to create the aperture (FIG. 43B).

A method for compensating a displayed image for small color shiftscaused by changes in the transmittance of an electro-optic device hasbeen disclosed herein. This method is also applicable to imaging devicesutilizing variable transmittance electro-optic filters and/or variableelectro-optic apertures. Corrections can be made to the pixel color atthe imaging sensor based on known color deviations caused by theelectro-optic device during its transition from fully clear to fullydarkened including intermediate levels. These corrections can, forexample, be applied digitally during image processing based oncorrection functions for the primaries or alternatively look-up tables.

Modifications of the invention will occur to those skilled in the artand to those who make or use the invention. Therefore, it is understoodthat the embodiments shown in the drawings and described above aremerely for illustrative purposes and not intended to limit the scope ofthe invention, which is defined by the following claims as interpretedaccording to the principles of patent law, including the doctrine ofequivalents.

1. An electrochromic system comprising: an electrochromic elementcomprising: a front element comprising first and second surfaces; a rearelement comprising third and fourth surfaces, wherein said front andrear elements are sealably bonded together in a spaced-apartrelationship to define a chamber, such that said second surface and saidthird surface face one another; and an electrochromic medium containedin said chamber, wherein said electrochromic medium is adapted to be inat least a high transmittance state and a low transmittance state; and asensor device in optical communication with said electrochromic element;wherein light passing through said electrochromic element and receivedby said sensor device has at least a first primary and a second primary,and said first and second primaries each having a first hue (h_(ab))when received by said sensor device through said electrochromic elementin approximately said high transmittance state and a second hue(h_(ab)′) when viewed through said electrochromic element inapproximately said low transmittance state, wherein a change in saidfirst and second hues (Δh_(ab)) for both first and second primaries isless than approximately 31 degrees.
 2. The electrochromic system ofclaim 1, wherein said change in said first and second hues (Δh_(ab)) forboth said first and second primaries is less than approximately 25degrees.
 3. The electrochromic system of claim 1, wherein said change insaid first and second hues (Δh_(ab)) for both said first and secondprimaries is less than approximately 15 degrees.
 4. The electrochromicsystem of claim 1, wherein each of said first and second primaries has afirst color (u′,v′) when received through said electrochromic element inapproximately said high transmittance state and a second color (u′,v′)′when received through said electrochromic element in approximately saidlow transmittance state, and a difference in said first and secondcolors (ΔE_(u′,v′)) for said first and second primaries is less thanapproximately 0.06.
 5. The electrochromic system of claim 1, whereinsaid first primary is light having a red hue and said second primary islight having a green hue.
 6. The electrochromic system of claim 1,wherein both said first and second primaries exhibit said change in hue(Δh_(ab)) of less than approximately 31 degrees when received throughsaid electrochromic element in approximately said high transmittancestate and said electrochromic element in a transmittance stateintermediate to said high and low transmittance states.
 7. Theelectrochromic system of claim 1, wherein said sensor device is furtherconfigured to receive a third primary having a first hue (h_(ab)) whenreceived through said electrochromic element in approximately said hightransmittance state and a second hue (h_(ab)′) when received throughsaid electrochromic element in approximately said low transmittancestate, and a change in said first and second hues (Δh_(ab)) is less thanapproximately 41 degrees.
 8. The electrochromic system of claim 7,wherein said change in said first and second hues (Δh_(ab)) of saidthird primary is less than approximately 35 degrees.
 9. Theelectrochromic system of claim 7, wherein said change in said first andsecond hues (Δh_(ab)) of said third primary is less than approximately20 degrees.
 10. The electrochromic system of claim 7, wherein saidchange in said first and second hues (Δh_(ab)) of said third primary isless than approximately 10 degrees.
 11. The electrochromic system ofclaim 7, wherein said third primary has a first color (u′,v′) whenreceived through said electrochromic element in approximately said hightransmittance state and a second color (u′,v′)′ when received throughsaid electrochromic element in approximately said low transmittancestate, and a difference in said first and second colors (ΔE_(u′,v′)) forsaid third primary is less than approximately 0.05.
 12. Theelectrochromic system of claim 7, wherein said third primary is lighthaving a blue hue.
 13. The electrochromic system of claim 1, whereinsaid sensor device is further configured to receive a fourth primaryhaving a first hue (h_(ab)) when received through said electrochromicelement in approximately said high transmittance state and a second hue(h_(ab)′) when received through said electrochromic element inapproximately said low transmittance state, and a change in said firstand second hues (Δh_(ab)) is less than approximately 55 degrees.
 14. Theelectrochromic system of claim 13, wherein said change in said first andsecond hues (Δh_(ab)) for said fourth primary is less than approximately50 degrees.
 15. The electrochromic system of claim 13, wherein saidchange in said first and second hues (Δh_(ab)) for said fourth primaryis less than approximately 40 degrees.
 16. The electrochromic system ofclaim 13, wherein said change in said first and second hues (Δh_(ab))for said fourth primary is less than approximately 30 degrees.
 17. Theelectrochromic system of claim 13, wherein said change in said first andsecond hues (Δh_(ab)) for said fourth primary is less than approximately15 degrees.
 18. The electrochromic system of claim 13, wherein saidfourth primary has a first color (u′,v′) when received through saidelectrochromic element in approximately said high transmittance stateand a second color (u′,v′) when received through said electrochromicelement in approximately said low transmittance state, and a differencein said first and second colors (ΔE_(u′,v′)) for said fourth primary isless than approximately 0.05.
 19. The electrochromic system of claim 13,wherein said fourth primary is light having a yellow hue.
 20. Anelectro-optic system comprising: an electro-optic element comprising: afront element comprising first and second surfaces; a rear elementcomprising third and fourth surfaces; and an electro-optic medium inoptical communication between said front element and said rear element,wherein said electro-optic medium is configured to adjust between atleast a high transmittance state and a low transmittance state; and asensor device in optical communication with said electro-optic element,said display device; wherein said sensor device being is configured toreceive at least a first primary and a second primary, and said firstand second primaries each having a first hue (h_(ab)) when receivedthrough said electro-optic element in approximately said hightransmittance state and a second hue (h_(ab)′) when received throughsaid electro-optic element in approximately said low transmittancestate, wherein a change in said first and second hues (Δh_(ab)) for bothfirst and second primaries is less than approximately 31 degrees. 21.The electro-optic system of claim 20, wherein said change in said firstand second hues (Δh_(ab)) for both said first and second primaryprimaries is less than approximately 25 degrees.
 22. The electro-opticsystem of claim 20, wherein said change in said first and second hues(Δh_(ab)) for both said first and second primaries is less thanapproximately 15 degrees.
 23. The electro-optic system of claim 20,wherein each of said first and second primaries has a first color(u′,v′) when received through said electro-optic element inapproximately said high transmittance state and a second color (u′,v′)′when received through said electro-optic element in approximately saidlow transmittance state, and a difference in said first and secondcolors (ΔE_(u′,v′)) for said first and second primaries is less thanapproximately 0.06.
 24. The electro-optic system of claim 20, whereinsaid first primary is light having a red hue and said second primary islight having a green hue.
 25. The electro-optic system of claim 20,wherein both said first and second primaries exhibit said change in hue(Δh_(ab)) of less than approximately 31 degrees when received throughsaid electro-optic element approximately in said high transmittancestate and said electro-optic element in a transmittance stateintermediate to said high and low transmittance states.
 26. Theelectro-optic system of claim 20, wherein said sensor device is furtherconfigured to receive a third primary having a first hue (h_(ab)) whenreceived through said electro-optic element in approximately said hightransmittance state and a second hue (h_(ab)′) when received throughsaid electro-optic element in approximately said low transmittancestate, and a change in said first and second hues (Δh_(ab)) is less thanapproximately 41 degrees.
 27. The electro-optic system of claim 26,wherein said change in said first and second hues (Δh_(ab)) of saidthird primary is less than approximately 35 degrees.
 28. Theelectro-optic system of claim 26, wherein said change in said first andsecond hues (Δh_(ab)) of said third primary is less than approximately20 degrees.
 29. The electro-optic system of claim 26, wherein saidchange in said first and second hues (Δh_(ab)) of said third primary isless than approximately 10 degrees.
 30. The electro-optic system ofclaim 26, wherein said third primary has a first color (u′,v′) whenreceived through said electro-optic element in approximately said hightransmittance state and a second color (u′,v′)′ when received throughsaid electro-optic element in approximately said low transmittancestate, and a difference in said first and second colors (ΔE_(u′,v′)) forsaid third primary is less than approximately 0.05.
 31. Theelectro-optic system of claim 26, wherein said third primary is lighthaving a blue hue.
 32. The electro-optic system of claim 20, whereinsaid sensor device is further configured to receive a fourth primaryhaving a first hue (h_(ab)) when received through said electro-opticelement in approximately said high transmittance state and a second hue(h_(ab)′) when received through said electro-optic element inapproximately said low transmittance state, and a change in said firstand second hues (Δh_(ab)) is less than approximately 55 degrees.
 33. Theelectro-optic system of claim 32, wherein said change in said first andsecond hues (Δh_(ab)) for said fourth primary is less than approximately50 degrees.
 34. The electro-optic system of claim 32, wherein saidchange in said first and second hues (Δh_(ab)) for said fourth primaryis less than approximately 40 degrees.
 35. The electro-optic system ofclaim 32, wherein said change in said first and second hues (Δh_(ab))for said fourth primary is less than approximately 30 degrees.
 36. Theelectro-optic system of claim 32, wherein said change in said first andsecond hues (Δh_(ab)) for said fourth primary is less than approximately15 degrees.
 37. The electro-optic system of claim 32, wherein saidfourth primary has a first color (u′,v′) when received through saidelectro-optic element in approximately said high transmittance state anda second color (u′,v′)′ when received through said electro-optic elementin approximately said low transmittance state, and a difference in saidfirst and second colors (ΔE_(u′,v′)) for said fourth primary is lessthan approximately 0.05.
 38. The electro-optic system of claim 32,wherein said fourth primary is light having a yellow hue.
 39. Aelectrochromic system comprising: an electrochromic element comprising:a front element comprising first and second surfaces; a rear elementcomprising third and fourth surfaces, wherein said front and rearelements are sealably bonded together in a spaced-apart relationship todefine a chamber, such that said second surface and said third surfaceface one another; and an electrochromic medium contained in saidchamber, wherein said electrochromic medium is adapted to be in at leasta high transmittance state and a low transmittance state; and a sensordevice in optical communication with said electrochromic element;wherein said sensor device is configured to receive at least one primarythat is light having at least one of a yellow hue and an amber hue, andsaid at least one primary having a first hue (h_(ab)) when receivedthrough said electrochromic element in approximately said hightransmittance state and a second hue (h_(ab)′) when received throughsaid electrochromic device in approximately the low transmittance state,wherein a change in said first and second hues (Δh_(ab)) is less thanapproximately 55 degrees.
 40. An electrochromic system comprising: anelectrochromic element comprising: a front element comprising first andsecond surfaces; a rear element comprising third and fourth surfaces,wherein said front and rear elements are sealably bonded together in aspaced-apart relationship to define a chamber, such that said secondsurface and said third surface face one another; and an electrochromicmedium contained in said chamber, wherein said electrochromic medium isadapted to be in at least a high transmittance state and a lowtransmittance state; and a sensor device in optical communication withsaid electrochromic element; wherein said sensor device is configured toreceive a primary that is light having a blue hue, and said primaryhaving a first hue (h_(ab)) when received through said electrochromicelement in approximately said high transmittance state and a second hue(h_(ab)′) when received through said electrochromic device inapproximately the low transmittance state, wherein a change in saidfirst and second hues (Δh_(ab)) is less than approximately 49 degrees.